A343112 Numbers having exactly 1 divisor of the form 8*k + 3.

3, 6, 9, 11, 12, 15, 18, 19, 21, 22, 24, 30, 35, 36, 38, 39, 42, 43, 44, 45, 48, 55, 59, 60, 63, 67, 69, 70, 72, 76, 77, 78, 83, 84, 86, 87, 88, 90, 91, 93, 95, 96, 107, 110, 111, 115, 117, 118, 120, 121, 126, 131, 133, 134, 138, 139, 140, 141, 143, 144

Offset

1,1

Links

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

Example

63 is a term since among the divisors of 63 (namely 1, 3, 7, 9, 21 and 63), the only divisor congruent to 3 modulo 8 is 3.

Prog

(PARI) res(n, a, b) = sumdiv(n, d, (d%a) == b)
isA343112(n) = (res(n, 8, 3) == 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), this sequence (m=1, i=3), A343113 (m=1, i=5), A141164 (m=1, i=7).

Indices of 1 in A188170.

A007520 is a subsequence.

Sequence in context: A000408 A025321 A153238 * A230193 A201462 A189302

Adjacent sequences: A343109 A343110 A343111 * A343113 A343114 A343115

Keyword

nonn,easy

Author

Jianing Song, Apr 05 2021

Status

approved