A057952 - OEIS

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A057952

Number of prime factors of 9^n - 1 (counted with multiplicity).

17

3, 5, 5, 7, 6, 8, 5, 10, 8, 10, 7, 11, 5, 9, 11, 12, 8, 12, 7, 13, 11, 11, 6, 17, 10, 9, 13, 13, 9, 17, 8, 14, 12, 12, 11, 16, 8, 11, 15, 18, 8, 18, 6, 16, 19, 10, 10, 21, 12, 18, 15, 13, 8, 18, 15, 19, 15, 13, 7, 24, 7, 13, 19, 16, 12, 18, 8, 17, 15, 20, 9, 24, 9, 13, 22, 17, 13, 22

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OFFSET

1,1

LINKS

Max Alekseyev, Table of n, a(n) for n = 1..690 (first 330 terms from Amiram Eldar)

S. S. Wagstaff, Jr., The Cunningham Project

FORMULA

Mobius transform of A085034. - T. D. Noe, Jun 19 2003

a(n) = A001222(A024101(n)) = A057958(2*n). - Amiram Eldar, Feb 02 2020

a(n) = A057941(n) + A057958(n). - Max Alekseyev, Jan 07 2024

MATHEMATICA

PrimeOmega[Table[9^n - 1, {n, 1, 30}]] (* Amiram Eldar, Feb 02 2020 *)

CROSSREFS

bigomega(b^n-1): A046051 (b=2), A057958 (b=3), A057957 (b=4), A057956 (b=5), A057955 (b=6), A057954 (b=7), A057953 (b=8), this sequence (b=9), A057951 (b=10), A366682 (b=11), A366708 (b=12).

Cf. A001222, A002591, A024101, A074477, A085034, A133801, A274909, A366660, A366661, A366662.

Sequence in context: A103988 A285204 A086269 * A175767 A111800 A190136

Adjacent sequences: A057949 A057950 A057951 * A057953 A057954 A057955

KEYWORD

nonn

AUTHOR

Patrick De Geest, Nov 15 2000

STATUS

approved