A064752 a(n) = n*6^n - 1.
5, 71, 647, 5183, 38879, 279935, 1959551, 13436927, 90699263, 604661759, 3990767615, 26121388031, 169789022207, 1097098297343, 7052774768639, 45137758519295, 287753210560511, 1828079220031487, 11577835060199423, 73123168801259519, 460675963447934975, 2895677484529876991
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
- Paul Leyland, Factors of Cullen and Woodall numbers.
- Paul Leyland, Generalized Cullen and Woodall numbers.
- Index entries for linear recurrences with constant coefficients, signature (13,-48,36).
Programs
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Magma
[ n*6^n-1: n in [1..20]]; // Vincenzo Librandi, Sep 16 2011
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Mathematica
Table[n 6^n-1,{n,25}] (* or *) LinearRecurrence[{13,-48,36},{5,71,647}, 25] (* Harvey P. Dale, May 25 2011 *)
Formula
From Harvey P. Dale, May 25 2011: (Start)
a(n) = 13*a(n-1) - 48*a(n-2) + 36*a(n-3); a(1)=5, a(2)=71, a(3)=647.
G.f.: 6*x/(1-6*x)^2 + x/(x-1). (End)
From Elmo R. Oliveira, May 05 2025: (Start)
E.g.f.: 1 + exp(x)*(6*x*exp(5*x) - 1).
a(n) = A036292(n) - 1. (End)