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A102359
a(n) = sigma((4^n - 1)/3), where sigma(n) is the sum of positive divisors of n.
3
1, 6, 32, 108, 384, 2688, 5632, 27864, 153920, 499968, 1477440, 11708928, 22380544, 115568640, 620101632, 1826150832, 5726797824, 54044390400, 91626668032, 555102471168, 2352412508160, 7458459886080, 23955459951744, 199536712962048, 425355918188544, 1849167560835072
OFFSET
1,2
LINKS
FORMULA
a(n) = A000203(A002450(n)). - Amiram Eldar, Feb 21 2020
PROG
(PARI) a(n) = sigma((4^n - 1)/3); \\ Michel Marcus, Feb 21 2020
CROSSREFS
Sequence in context: A288961 A090382 A360839 * A000397 A200765 A239573
KEYWORD
nonn
AUTHOR
Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Feb 22 2005
EXTENSIONS
More terms from Amiram Eldar, Feb 21 2020
STATUS
approved