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A270567
Expansion of (1+4*x)/(1-5*x).
2
1, 9, 45, 225, 1125, 5625, 28125, 140625, 703125, 3515625, 17578125, 87890625, 439453125, 2197265625, 10986328125, 54931640625, 274658203125, 1373291015625, 6866455078125, 34332275390625, 171661376953125, 858306884765625, 4291534423828125, 21457672119140625
OFFSET
0,2
COMMENTS
Partial sums are 1, 10, 55, 280, 1405, 7030, ...
Apparently a duplicate of A189274. - R. J. Mathar, May 13 2016
FORMULA
G.f.: (1+4*x) / (1-5*x).
a(n) = 5*a(n-1) for n>1.
a(n) = 9*5^(n-1) for n>0.
MATHEMATICA
CoefficientList[Series[(1 + 4 x)/(1 - 5 x), {x, 0, 23}], x] (* Michael De Vlieger, Mar 19 2016 *)
PROG
(PARI) Vec((1+4*x)/(1-5*x) + O(x^30))
CROSSREFS
Cf. A000351 (powers of 5), A128625 (1+3*x)/(1-5*x), A189274.
Sequence in context: A255965 A180796 A189274 * A316108 A026092 A054628
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Mar 19 2016
STATUS
approved