# History function

Can you tell the next element of this history function?

It is meant and important that mathematics tag isn't here!

I save you the time to search on OEIS, you won't find it :)

PS: I did post this puzzle yesterday but I replaced it with this one with improvements :)

• 1950 $$\rightarrow$$ 0
• 1951 $$\rightarrow$$ 1
• 1952 $$\rightarrow$$ 1
• 1953 $$\rightarrow$$ 2
• 1954 $$\rightarrow$$ 2
• 1955 $$\rightarrow$$ 0
• 1956 $$\rightarrow$$ 1
• 1957 $$\rightarrow$$ 1
• 1958 $$\rightarrow$$ 4
• 1959 $$\rightarrow$$ 2
• 1960 $$\rightarrow$$ 3
• 1961 $$\rightarrow$$ 1
• 1962 $$\rightarrow$$ 2
• 1963 $$\rightarrow$$ 3
• 1964 $$\rightarrow$$ 3
• 1965 $$\rightarrow$$ 3
• 1966 $$\rightarrow$$ 2
• 1967 $$\rightarrow$$ 4
• 1968 $$\rightarrow$$ 5
• 1969 $$\rightarrow$$ 4
• 1970 $$\rightarrow$$ 6
• 1971 $$\rightarrow$$ 4
• 1972 $$\rightarrow$$ 5
• 1973 $$\rightarrow$$ 8
• 1974 $$\rightarrow$$ 8
• 1975 $$\rightarrow$$ 7
• 1976 $$\rightarrow$$ 9
• 1977 $$\rightarrow$$ 10
• 1978 $$\rightarrow$$ 9
• 1979 $$\rightarrow$$ 8
• 1980 $$\rightarrow$$ 7
• 1981 $$\rightarrow$$ 8
• 1982 $$\rightarrow$$ 9
• 1983 $$\rightarrow$$ 8
• 1984 $$\rightarrow$$ 9
• 1985 $$\rightarrow$$ 9
• 1986 $$\rightarrow$$ 9
• 1987 $$\rightarrow$$ 9
• 1988 $$\rightarrow$$ 9
• 1989 $$\rightarrow$$ 9
• 1990 $$\rightarrow$$ 9
• 1991 $$\rightarrow$$ 9
• 1992 $$\rightarrow$$ 9
• 1993 $$\rightarrow$$ 9
• 1994 $$\rightarrow$$ 9
• 1995 $$\rightarrow$$ 10
• 1996 $$\rightarrow$$ 9
• 1997 $$\rightarrow$$ 10
• 1998 $$\rightarrow$$ 9
• 1999 $$\rightarrow$$ 9
• 2000 $$\rightarrow$$ 10
• 2001 $$\rightarrow$$ 10
• 2002 $$\rightarrow$$ 10
• 2003 $$\rightarrow$$ 9
• 2004 $$\rightarrow$$ 11
• 2005 $$\rightarrow$$ 12
• 2006 $$\rightarrow$$ 11
• 2007 $$\rightarrow$$ 10
• 2008 $$\rightarrow$$ 11
• 2009 $$\rightarrow$$ 10
• 2010 $$\rightarrow$$ 12
• 2011 $$\rightarrow$$ 12
• 2012 $$\rightarrow$$ 13
• 2013 $$\rightarrow$$ 12
• 2014 $$\rightarrow$$ 12
• 2015 $$\rightarrow$$ 12
• 2016 $$\rightarrow$$ 14
• 2017 $$\rightarrow$$ 13
• 2018 $$\rightarrow$$ 14
• 2019 $$\rightarrow$$ 14
• 2020 $$\rightarrow$$ ?

Values: 0 1 1 2 2 0 1 1 4 2 3 1 2 3 3 3 2 4 5 4 6 4 5 8 8 7 9 10 9 8 7 8 9 8 9 9 9 9 9 9 9 9 9 9 9 10 9 10 9 9 10 10 10 9 11 12 11 10 11 10 12 12 13 12 12 12 14 13 14 14

# Hints

## 20 10 2020

Time for an hint!

All years before 1950 are valued to -7.

• Just for clarity: when you call it a "history function", are you specifically telling us that the year-like numbers do actually represent years? – Gareth McCaughan Oct 16 '20 at 10:44
• @GarethMcCaughan, yes! input numbers are years :) – JKHA Oct 16 '20 at 11:26
• With these years, and numbers in this ballpark, I've been so sure in my head that this is something to do with rot13(Sbezhyn 1) that I now can't see any other possibilities. I'm guessing it's not or I would have spotted it by now... Come on head, get empty again! – Stiv Oct 16 '20 at 12:06
• Is, for instance, binary calculation / observation (eg numbers of bits) considered as 'maths'? – Breaking not so bad Oct 16 '20 at 13:07
• @e2-e4, for math and computer-science tag, I could do the same remark :) I really like your nickname by the way ;) – JKHA Oct 16 '20 at 15:43