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A247787 Sum of divisors of 2*prime(n)-1. 2
4, 6, 13, 14, 32, 31, 48, 38, 78, 80, 62, 74, 121, 108, 128, 192, 182, 133, 160, 192, 180, 158, 288, 240, 194, 272, 252, 288, 256, 403, 288, 390, 448, 278, 480, 352, 314, 434, 494, 576, 576, 381, 512, 576, 528, 398, 422, 540, 608, 458, 768, 702, 532, 672 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
See A005382 (primes p such that sigma(2p-1) = 2p).
LINKS
FORMULA
a(n) = sigma(A076274(n)) = A000203(A076274(n)).
EXAMPLE
For n = 3; prime(3) = 5, a(3) = sigma(2*5-1) = sigma(9) = 13.
PROG
(Magma) [SumOfDivisors(2*p-1): p in PrimesUpTo(2000)]
(PARI) vector(100, n, sigma(2*prime(n)-1)) \\ Derek Orr, Sep 25 2014
CROSSREFS
Sequence in context: A225939 A191199 A354089 * A074165 A137821 A010061
KEYWORD
nonn,easy
AUTHOR
Jaroslav Krizek, Sep 24 2014
STATUS
approved

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Last modified April 12 14:01 EDT 2024. Contains 371635 sequences. (Running on oeis4.)