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A155181
a(n)=5*a(n-1)+a(n-2), n>2 ; a(0)=1, a(1)=4, a(2)=20 .
2
1, 4, 20, 104, 540, 2804, 14560, 75604, 392580, 2038504, 10585100, 54964004, 285405120, 1481989604, 7695353140, 39958755304, 207489129660, 1077404403604, 5594511147680, 29049960142004, 150844311857700, 783271519430504
OFFSET
0,2
FORMULA
G.f.: (1-x-x^2)/(1-5*x-x^2).
a(n) = Sum_{k=0..n} A155161(n,k)*4^k. - Philippe Deléham, Feb 08 2012
MATHEMATICA
LinearRecurrence[{5, 1}, {1, 4, 20}, 25] (* Paolo Xausa, Jan 19 2024 *)
CROSSREFS
Cf. A155161.
Sequence in context: A229135 A226198 A155485 * A082761 A076035 A120978
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Jan 21 2009
STATUS
approved