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A162962
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a(n) = 5*a(n-2) for n > 2; a(1) = 1, a(2) = 5.
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1
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1, 5, 5, 25, 25, 125, 125, 625, 625, 3125, 3125, 15625, 15625, 78125, 78125, 390625, 390625, 1953125, 1953125, 9765625, 9765625, 48828125, 48828125, 244140625, 244140625, 1220703125, 1220703125, 6103515625, 6103515625, 30517578125
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Apparently a(n) = A074872(n+1), a(n) = A056451(n-1) for n > 1.
Binomial transform is A084057 without initial 1, second binomial transform is A048876, third binomial transform is A082762, fourth binomial transform is A162769, fifth binomial transform is A093145 without initial 0.
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FORMULA
| a(n) = 5^((1/4)*(2*n-1+(-1)^n)).
G.f.: x*(1+5*x)/(1-5*x^2).
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PROG
| (MAGMA) [ n le 2 select 4*n-3 else 5*Self(n-2): n in [1..30] ];
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CROSSREFS
| Cf. A000351 (powers of 5), A074872 (powers of 5 repeated), A056451 (5^floor((n+1)/2)), A084057, A048876, A082762, A162769, A093145.
Sequence in context: A071340 A056451 A074872 * A170834 A154630 A038247
Adjacent sequences: A162959 A162960 A162961 * A162963 A162964 A162965
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KEYWORD
| nonn
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jul 19 2009
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