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A083425
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(5*5^n+(-1)^n)/6.
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3
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1, 4, 21, 104, 521, 2604, 13021, 65104, 325521, 1627604, 8138021, 40690104, 203450521, 1017252604, 5086263021, 25431315104, 127156575521, 635782877604, 3178914388021, 15894571940104, 79472859700521, 397364298502604
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Binomial transform of A083424. Inverse binomial transform of A052934.
Primes occur at indices n= 4, 66, 100, 102, 228, 346,.., see A138647. - R. J. Mathar, Jan 19 2011
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (4,5).
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FORMULA
| a(n)=(5*5^n+(-1)^n)/6.
G.f. 1/((1+x)(1-5x)).
E.g.f. (5exp(5x)+exp(-x))/6.
a(n)=sum{k=0..n, binomial(n-k, k)*4^(n-2k)*5^k} - Paul Barry (pbarry(AT)wit.ie), Jul 29 2004
a(n)=A015531(n+1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 17 2008]
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CROSSREFS
| Sequence in context: A113022 A014986 A015531 * A183367 A100237 A117381
Adjacent sequences: A083422 A083423 A083424 * A083426 A083427 A083428
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Apr 30 2003
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