A343113 Numbers having exactly 1 divisor of the form 8*k + 5.

5, 10, 13, 15, 20, 21, 25, 26, 29, 30, 35, 37, 39, 40, 42, 50, 52, 53, 55, 58, 60, 61, 63, 69, 70, 74, 75, 77, 78, 80, 84, 87, 91, 93, 95, 100, 101, 104, 106, 109, 110, 111, 115, 116, 120, 122, 126, 133, 138, 140, 141, 143, 147, 148, 149, 150, 154, 155

Offset

1,1

Links

Jianing Song, Table of n, a(n) for n = 1..10000

Example

52 is a term since among the divisors of 52 (namely 1, 2, 4, 13, 26 and 52), the only divisor congruent to 5 modulo 8 is 13.

Prog

(PARI) res(n, a, b) = sumdiv(n, d, (d%a) == b)
isA343113(n) = (res(n, 8, 5) == 1)

Crossrefs

Numbers having m divisors of the form 8*k + i: A343107 (m=1, i=1), A343108 (m=0, i=3), A343109 (m=0, i=5), A343110 (m=0, i=7), A343111 (m=2, i=1), A343112 (m=1, i=3), this sequence (m=1, i=5), A141164 (m=1, i=7).

Indices of 1 in A188171.

A007521 is a subsequence.

Sequence in context: A334757 A209922 A084645 * A354235 A313379 A092604

Adjacent sequences: A343110 A343111 A343112 * A343114 A343115 A343116

Keyword

nonn,easy

Author

Jianing Song, Apr 05 2021

Status

approved