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A034513 a(n) = 1^n + 3^n + 9^n. 88
3, 13, 91, 757, 6643, 59293, 532171, 4785157, 43053283, 387440173, 3486843451, 31381236757, 282430067923, 2541867422653, 22876797237931, 205891146443557, 1853020231898563, 16677181828806733, 150094635684419611 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
Also the sum of n-th powers of the divisors of 9.
LINKS
FORMULA
G.f.: 1/(1-x)+1/(1-3*x)+1/(1-9*x). E.g.f.: e^x+e^(3*x)+e^(9*x). - Mohammad K. Azarian, Dec 26 2008
a(n) = 13*a(n-1) - 39*a(n-2) + 27*a(n-3), a(0)=3, a(1)=13, a(2)=91. - Harvey P. Dale, Apr 13 2012
MATHEMATICA
Table[1^n + 3^n + 9^n, {n, 0, 20}]
LinearRecurrence[{13, -39, 27}, {3, 13, 91}, 20] (* Harvey P. Dale, Apr 13 2012 *)
PROG
(Sage) [sigma(9, n)for n in range(0, 19)] # Zerinvary Lajos, Jun 04 2009
(PARI) a(n)=1+3^n+9^n \\ Charles R Greathouse IV, Jun 10 2011
CROSSREFS
Sequence in context: A345104 A116434 A174290 * A257661 A292501 A243243
KEYWORD
easy,nonn
AUTHOR
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)