A278781 Numbers m such that A000041(m) is of the form 2^4 * k for odd k.

15, 106, 122, 131, 136, 253, 295, 327, 339, 383, 412, 449, 465, 517, 520, 551, 580, 581, 599, 602, 632, 648, 669, 677, 776, 806, 815, 838, 904, 927, 1071, 1137, 1166, 1174, 1199, 1263, 1275, 1298, 1325, 1375, 1399, 1404, 1425, 1554, 1564, 1641, 1684, 1688

Offset: 1

Author

Colin Barker, Nov 28 2016

Keywords

• nonn

Comments

Numbers m such that A278478(m) = 4.

Also numbers m such that A000041(m) has four times as many even divisors as odd divisors.

Links

• Colin Barker, Table of n, a(n) for n = 1..600

Crossrefs

Cf. A000041, A278198, A278779, A278780, A278782, A278783, A278784.

Positions of 4's in A278478.

Programs

Mathematica

Select[Range[1700], IntegerExponent[PartitionsP[#], 2] == 4 &] (* Amiram Eldar, May 25 2024 *)

PARI

isok(n) = valuation(numbpart(n), 2)==4;
select(n->isok(n), vector(2000, n, n))

Formula

A000041(a(n)) = A278198(n).