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A162281 Values of sigma_0(n) for n in A162279. 2
4, 4, 4, 4, 4, 8, 4, 8, 4, 4, 4, 4, 8, 4, 8, 4, 4, 8, 4, 4, 8, 12, 4, 8, 4, 8, 4, 4, 4, 8, 6, 4, 4, 8, 4, 8, 12, 4, 4, 4, 8, 4, 4, 4, 4, 8, 4, 8, 12, 4, 4, 8, 16, 4, 8, 12, 4, 8, 4, 6, 4, 4, 12, 4, 8, 4, 4, 8, 4, 12, 4, 8, 4, 8, 12, 4, 4, 8, 6, 4, 8, 16, 12, 4, 4, 4, 4, 8, 4, 12, 4, 8, 4, 4, 8, 4, 8, 12, 4, 8 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

No primes can appear in this sequence; to have sigma_0(n) = p, a prime, we must have n = q^{p-1} for some prime q, and each such n for fixed p will have a distinct value for sigma(n).

Conjecture: every composite number appears in this sequence. - Max Alekseyev (maxale(AT)gmail.com)

Up to sigma(n) = 500000, the only odd value is 9, for 106276 = 326^2 and 165649 = 407^2; these have sigma(n) = 187131.

LINKS

Franklin T. Adams-Watters, Table of duplicate sigma values up to sigma(n) = 10000

FORMULA

a(n) = A000005(A162279(n)) = A000005(A162280(n)).

CROSSREFS

Cf. A000005, A162279.

Sequence in context: A085142 A064053 A108893 * A048760 A035627 A165923

Adjacent sequences:  A162278 A162279 A162280 * A162282 A162283 A162284

KEYWORD

nonn

AUTHOR

Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Jun 29 2009

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Last modified February 16 17:11 EST 2012. Contains 205938 sequences.