A382546 Positive integers whose prime factors are all in A219528.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 60, 62, 63, 64, 65, 66, 68, 69, 70, 71, 72, 73, 74, 75

Offset

1,2

Links

Steven Lu, Table of n, a(n) for n = 1..10000

Formula

Sum_{n>=1} 1/a(n) = 1/Product_{p in A219528} (1-1/p) = 7.52982574262479641306... . - Amiram Eldar, Apr 14 2025

Mathematica

Select[Range[75], And @@ Table[SubsetQ[{2, 3}, First /@ FactorInteger[p + 1]] || SubsetQ[{2, 3}, First /@ FactorInteger[p - 1]], {p, First /@ FactorInteger[#]}] &]

Crossrefs

Cf. A219528.

Sequence in context: A194906 A160546 A356944 * A087143 A395630 A080683

Adjacent sequences: A382543 A382544 A382545 * A382547 A382548 A382549

Keyword

nonn

Author

Steven Lu, Mar 31 2025

Status

approved