A195291 Years in the Gregorian calendar which are not (proleptic) leap years.

1, 2, 3, 5, 6, 7, 9, 10, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 25, 26, 27, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 45, 46, 47, 49, 50, 51, 53, 54, 55, 57, 58, 59, 61, 62, 63, 65, 66, 67, 69, 70, 71, 73, 74, 75, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89, 90, 91, 93, 94, 95, 97, 98, 99, 100

Offset: 1

Author

Kausthub Gudipati, Sep 16 2011

Keywords

• nonn
• easy

Comments

If n does not exactly divide 100, n should exactly divide 4.

If n exactly divides 100, n should exactly divide 400.

Links

• Index entries for linear recurrences with constant coefficients, order 304.
• Index entries for sequences related to calendars

Crossrefs

Cf. A042968.

Programs

Mathematica

Select[Range[100],!LeapYearQ[{#}]&] (* Harvey P. Dale, Jan 01 2019 *)

PARI

is(n)=n%4||(n%100==0&&n%400) \\ Charles R Greathouse IV, Sep 18 2011

Formula

a(n) = a(n-1) + a(n-303) - a(n-304). [Charles R Greathouse IV, Sep 18 2011]