A332801 - OEIS

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A332801

a(n) is the number of even results of n mod k, for 1 < k < n.

0, 0, 0, 1, 1, 3, 1, 4, 3, 5, 3, 7, 3, 9, 5, 8, 6, 11, 5, 13, 7, 13, 7, 15, 8, 16, 10, 16, 10, 20, 8, 21, 11, 21, 13, 22, 12, 24, 14, 24, 14, 28, 12, 30, 16, 28, 16, 30, 17, 32, 18, 32, 18, 36, 18, 36, 20, 36, 20, 40, 18, 42, 22, 39, 25, 41, 23, 43, 25, 45, 23, 48, 22, 50

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,6

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

n(7) = 1 because only 7 mod 5 = 2 is even.

MATHEMATICA

Table[Total[Boole[EvenQ/@Mod[n, Range[2, n-1]]]], {n, 80}] (* Harvey P. Dale, Aug 09 2021 *)

PROG

(PARI) a(n) = sum(k=2, n-1, ((n % k) % 2)== 0); \\ Michel Marcus, Feb 24 2020

CROSSREFS