A326049 a(n) = n - A050449(n), where A050449 is the sum of divisors of the form 4k+1.

0, 1, 2, 3, -1, 5, 6, 7, -1, 4, 10, 11, -1, 13, 9, 15, -1, 8, 18, 14, -1, 21, 22, 23, -6, 12, 17, 27, -1, 24, 30, 31, -1, 16, 29, 26, -1, 37, 25, 34, -1, 20, 42, 43, -15, 45, 46, 47, -1, 19, 33, 38, -1, 44, 49, 55, -1, 28, 58, 54, -1, 61, 32, 63, -19, 32, 66, 50, -1, 64, 70, 62, -1, 36, 44, 75, -1, 64, 78, 74, -10, 40

Offset: 1

Author

Antti Karttunen, Jun 04 2019

Keywords

• sign

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A033879, A050449, A326047, A326048, A326050, A326052.

Programs

PARI

A050449(n) = sumdiv(n, d, d*((d % 4) == 1)); \\ From A050449
A326049(n) = (n-A050449(n));

Formula

a(n) = n - A050449(n).

a(n) = A326050(n) + A033879(n).