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

Author

Klaus Brockhaus, Jul 19 2009

Keywords

• nonn
• easy

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

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

Crossrefs

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

Programs

Magma

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

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.