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A338506
a(n) is the number of subsets of divisors of n.
1
2, 4, 4, 8, 4, 16, 4, 16, 8, 16, 4, 64, 4, 16, 16, 32, 4, 64, 4, 64, 16, 16, 4, 256, 8, 16, 16, 64, 4, 256, 4, 64, 16, 16, 16, 512, 4, 16, 16, 256, 4, 256, 4, 64, 64, 16, 4, 1024, 8, 64, 16, 64, 4, 256, 16, 256, 16, 16, 4, 4096, 4, 16, 64, 128, 16, 256, 4, 64
OFFSET
1,1
COMMENTS
In contrast to A100587, we take into account the empty set.
LINKS
FORMULA
a(n) = 2^A000005(n) = A100587(n) + 1.
EXAMPLE
For n = 6:
- 6 has 4 divisors,
- so a(n) = 2^4 = 16.
MATHEMATICA
Table[2^DivisorSigma[0, n], {n, 68}]
PROG
(PARI) a(n) = 2^numdiv(n)
CROSSREFS
Sequence in context: A140434 A308605 A107748 * A353190 A005884 A229913
KEYWORD
nonn,easy
AUTHOR
Rémy Sigrist, Oct 31 2020
STATUS
approved