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A072056 Number of divisors of 2*prime(n)+1. 2
2, 2, 2, 4, 2, 4, 4, 4, 2, 2, 6, 6, 2, 4, 4, 2, 4, 4, 8, 4, 6, 4, 2, 2, 8, 4, 6, 4, 4, 2, 8, 2, 6, 6, 4, 4, 12, 4, 4, 2, 2, 6, 2, 6, 4, 8, 6, 4, 8, 8, 2, 2, 8, 2, 4, 4, 6, 4, 8, 2, 10, 2, 8, 4, 8, 4, 8, 12, 4, 4, 4, 2, 12, 6, 8, 4, 4, 8, 4, 12, 2, 4, 2, 6, 4, 2, 4, 8, 4, 6, 8, 4, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..93.

EXAMPLE

Divisors of A072055(8)=2*A000040(8)+1=2*19+1=39: {1,3,13,39} with size 4, therefore a(8)=4.

MATHEMATICA

Table[DivisorSigma[0, 2Prime[n]+1], {n, 100}] (* Harvey P. Dale, Apr 12 2021 *)

CROSSREFS

a(n)=A000005(A072055(n)), A000040, A072057.

Sequence in context: A161841 A335901 A152674 * A066012 A063375 A064129

Adjacent sequences:  A072053 A072054 A072055 * A072057 A072058 A072059

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 11 2002

STATUS

approved

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Last modified October 16 23:07 EDT 2021. Contains 348047 sequences. (Running on oeis4.)