A372468 The number of divisors of the numbers whose number of divisors is a power of 2 (A036537).

1, 2, 2, 2, 4, 2, 4, 4, 2, 2, 4, 4, 2, 2, 4, 4, 2, 8, 4, 4, 2, 8, 2, 4, 4, 4, 2, 4, 4, 8, 2, 8, 2, 4, 2, 4, 2, 8, 4, 8, 4, 4, 2, 2, 4, 4, 8, 2, 4, 8, 2, 2, 4, 4, 8, 2, 4, 2, 4, 4, 4, 8, 2, 4, 4, 4, 4, 2, 2, 8, 2, 8, 8, 4, 2, 2, 8, 4, 2, 8, 4, 4, 4, 16, 4, 4, 4

Offset

1,2

Comments

Also, the number of infinitary divisors of the numbers whose number of divisors is a power of 2.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000005(A036537(n)).

a(n) = A037445(A036537(n)).

a(n) = A372470(A036537(n)).

a(n) = 2^A372469(n).

Mathematica

Select[DivisorSigma[0, Range[300]], # == 2^IntegerExponent[#, 2] &]

Prog

(PARI) lista(n) = select(x -> x >> valuation(x, 2) == 1, vector(n, i, numdiv(i)));

Crossrefs

Cf. A000005, A036537, A037445, A372469, A372470.

Sequence in context: A072048 A161841 A335901 * A366438 A152674 A072056

Adjacent sequences: A372465 A372466 A372467 * A372469 A372470 A372471

Keyword

nonn,easy

Author

Amiram Eldar, May 02 2024

Status

approved