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A274072
a(n) = 5^n-(-1)^n.
2
0, 6, 24, 126, 624, 3126, 15624, 78126, 390624, 1953126, 9765624, 48828126, 244140624, 1220703126, 6103515624, 30517578126, 152587890624, 762939453126, 3814697265624, 19073486328126, 95367431640624, 476837158203126, 2384185791015624, 11920928955078126
OFFSET
0,2
FORMULA
O.g.f.: 6*x/((1+x)*(1-5*x)).
E.g.f.: exp(5*x) - exp(-x).
a(n) = 4*a(n-1) + 5*a(n-2) for n>1.
a(n) = 6*A015531(n).
MATHEMATICA
LinearRecurrence[{4, 5}, {0, 6}, 30] (* Paolo Xausa, Oct 21 2024 *)
PROG
(PARI) concat(0, Vec(6*x/((1+x)*(1-5*x)) + O(x^30)))
CROSSREFS
Cf. A015531.
Sequences of the type k^n-(-1)^n: A062157 (k=0), A010673 (k=1), A062510 (k=2), A105723 (k=3), A247281 (k=4), this sequence (k=5), A274073 (k=6).
Sequence in context: A357192 A357194 A188232 * A224662 A200160 A219622
KEYWORD
nonn,easy,changed
AUTHOR
Colin Barker, Jun 09 2016
STATUS
approved