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A102360 a(n) = sigma((7^n - 1)/6), where sigma(n) is the sum of positive divisors of n. 1
1, 15, 80, 961, 2802, 52800, 142020, 2347506, 10512320, 96837120, 329849040, 8619170560, 16148168402, 221483030400, 1146781040640, 14442767744328, 38774519976900, 813898294809600, 1904350030969680, 35410174950039552 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..378

FORMULA

a(n) = A000203(A023000(n)). - Amiram Eldar, Feb 21 2020

PROG

(PARI) a(n) = sigma((7^n - 1)/6); \\ Michel Marcus, Feb 21 2020

CROSSREFS

Cf. A000203, A023000.

Sequence in context: A055815 A338414 A244855 * A309336 A266288 A213552

Adjacent sequences:  A102357 A102358 A102359 * A102361 A102362 A102363

KEYWORD

nonn

AUTHOR

Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Feb 22 2005

STATUS

approved

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Last modified April 22 16:32 EDT 2021. Contains 343177 sequences. (Running on oeis4.)