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A188526
a(n) = 3^(2*n + 3) + 2^n.
2
28, 245, 2191, 19691, 177163, 1594355, 14348971, 129140291, 1162261723, 10460353715, 94143179851, 847288611491, 7625597489083, 68630377373075, 617673396300331, 5559060566588291, 50031545099065243, 450283905891128435, 4052555153019238411
OFFSET
0,1
COMMENTS
All terms are multiples of 7: A082784(a(n)) = 1, A188527(n) = a(n)/7.
REFERENCES
Kees Doets and Jan van Eijck, The Haskell Road to Logic, Maths and Programming, The King's College Publications, London 2006. Cf. exercise 7.9, p 239.
FORMULA
a(n) = A013708(n+1) + A000079(n).
G.f.: 7*(4-9*x)/((1-2*x)*(1-9*x)). - Bruno Berselli, Jul 17 2011
MATHEMATICA
Table[3^(2n+3)+2^n, {n, 0, 20}] (* Harvey P. Dale, Apr 09 2011 *)
PROG
(Magma) [3^(2*n + 3) + 2^n: n in [0..20]]; // Vincenzo Librandi, Jul 17 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Reinhard Zumkeller, Apr 03 2011
STATUS
approved