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A009986
Powers of 42.
6
1, 42, 1764, 74088, 3111696, 130691232, 5489031744, 230539333248, 9682651996416, 406671383849472, 17080198121677824, 717368321110468608, 30129469486639681536, 1265437718438866624512, 53148384174432398229504, 2232232135326160725639168, 93753749683698750476845056
OFFSET
0,2
COMMENTS
Same as Pisot sequences E(1, 42), L(1, 42), P(1, 42), T(1, 42). Essentially same as Pisot sequences E(42, 1764), L(42, 1764), P(42, 1764), T(42, 1764). See A008776 for definitions of Pisot sequences.
The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n >= 1, a(n) equals the number of 42-colored compositions of n such that no adjacent parts have the same color. - Milan Janjic, Nov 17 2011
FORMULA
G.f.: 1/(1-42*x). - Philippe Deléham, Nov 24 2008
a(n) = 42^n; a(n) = 42*a(n-1), a(0)=1. - Vincenzo Librandi, Nov 21 2010
From Elmo R. Oliveira, Jul 10 2025: (Start)
E.g.f.: exp(42*x).
a(n) = A000079(n)*A009965(n) = A000400(n)*A000420(n). (End)
MATHEMATICA
42^Range[0, 14] (* Michael De Vlieger, Jan 13 2018 *)
PROG
(Magma)[42^n: n in [0..20]]; // Vincenzo Librandi, Nov 21 2010
(PARI) a(n) = 42^n; \\ Michel Marcus, Jan 14 2018
CROSSREFS
KEYWORD
nonn,easy
STATUS
approved