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1, 4, 10, 28, 82, 244, 730, 2188, 6562, 19684, 59050, 177148, 531442, 1594324, 4782970, 14348908, 43046722, 129140164, 387420490, 1162261468, 3486784402, 10460353204, 31381059610, 94143178828, 282429536482, 847288609444
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| P. De Geest, World!Of Numbers
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FORMULA
| G.f.: (1-3x^2)/((1-x)(1-3x)); a(n)=sum{k=0..n, binomial(n, k)*0^(k(n-k))*3^k}.
a(n)=A034472(n), n>0. a(n)=A094388(n-1), n>1. a(n+1)-a(n)=A110593(n+1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 04 2008]
a(n)=3*a(n-1)-2, with a(1)=4. [From Vincenzo Librandi, Dec 29 2010]
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CROSSREFS
| Cf. A034772, A046231.
Sequence in context: A026150 A026123 A091468 * A083587 A061639 A008995
Adjacent sequences: A103454 A103455 A103456 * A103458 A103459 A103460
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Feb 07 2005
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