A162963 a(n) = 5*a(n-2) for n > 2; a(1) = 2, a(2) = 5.

2, 5, 10, 25, 50, 125, 250, 625, 1250, 3125, 6250, 15625, 31250, 78125, 156250, 390625, 781250, 1953125, 3906250, 9765625, 19531250, 48828125, 97656250, 244140625, 488281250, 1220703125, 2441406250, 6103515625, 12207031250

Offset

1,1

Comments

Binomial transform is A162770, second binomial transform is A001077 without initial 1, third binomial transform is A162771, fourth binomial transform is A162772, fifth binomial transform is A162773.

Links

Table of n, a(n) for n=1..29.

Index entries for linear recurrences with constant coefficients, signature (0,5).

Formula

a(n) = (3-(-1)^n)*5^(1/4*(2*n-1+(-1)^n))/2.

G.f.: x*(2+5*x)/(1-5*x^2).

a(n) = A026383(n) for n >= 1.

Prog

(Magma) [ n le 2 select 3*n-1 else 5*Self(n-2): n in [1..29] ];

Crossrefs

Cf. A000351 (powers of 5), A026383, A001077, A162770, A162771, A162772, A162773.

Sequence in context: A336542 A018356 A026383 * A297860 A002094 A212709

Adjacent sequences: A162960 A162961 A162962 * A162964 A162965 A162966

Keyword

nonn,easy

Author

Klaus Brockhaus, Jul 19 2009

Status

approved