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A093175
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Tetranacci numbers starting with first four squares.
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0
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1, 4, 9, 16, 30, 59, 114, 219, 422, 814, 1569, 3024, 5829, 11236, 21658, 41747, 80470, 155111, 298986, 576314, 1110881, 2141292, 4127473, 7955960, 15335606, 29560331, 56979370, 109831267, 211706574, 408077542, 786594753, 1516210136, 2922589005
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4).
G.f.: -x*(1+x)*(2*x^2+2*x+1)/(-1+x+x^2+x^3+x^4). a(n)=2*A000078(n+3)+2*A000078(n)-A001631(n+1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 20 2009]
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MATHEMATICA
| a[1] = 1; a[2] = 4; a[3] = 9; a[4] = 16; a[n_] := a[n] = a[n - 1] + a[n - 2] + a[n - 3] + a[n - 4]; Table[ a[n], {n, 33}] (from Robert G. Wilson v)
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CROSSREFS
| Cf. A086192.
Sequence in context: A001640 A161328 A073141 * A138992 A199936 A007679
Adjacent sequences: A093172 A093173 A093174 * A093176 A093177 A093178
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KEYWORD
| nonn
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AUTHOR
| Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), May 11 2004
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and Labos E. (labos(AT)ana.sote.hu), May 12 2004, May 11 2004
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