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A140994
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Triangle read by rows: recurrence G(n,k): G(n, n)=G(n+1, 0)=1, G(n+2, 1)=2, G(n+3, 2)=4, G(n+4, k)=G(n+1, k-2)+G(n+1, k-3)+G(n+2, k-2)+G(n+3, k-1) for k:=3..(n+3), 0<=k<=n.
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1
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1, 1, 1, 1, 2, 1, 1, 2, 4, 1, 1, 2, 4, 8, 1, 1, 2, 4, 9, 15, 1, 1, 2, 4, 9, 19, 28, 1, 1, 2, 4, 9, 19, 40, 52, 1, 1, 2, 4, 9, 19, 41, 83, 96, 1, 1, 2, 4, 9, 19, 41, 88, 170, 177, 1, 1, 2, 4, 9, 19, 41, 88, 188, 345, 326, 1, 1, 2, 4, 9, 19, 41, 88, 189, 400, 694, 600, 1, 1, 2, 4, 9, 19, 41, 88
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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EXAMPLE
| Triangle begins:
1
1 1
1 2 1
1 2 4 1
1 2 4 8 1
1 2 4 9 15 1
1 2 4 9 19 28 1
1 2 4 9 19 40 52 1
1 2 4 9 19 41 83 96 1
1 2 4 9 19 41 88 170 177 1
1 2 4 9 19 41 88 188 345 326 1
1 2 4 9 19 41 88 189 400 694 400 1
1 2 4 9 19 41 88 189 406 1846 1386 1104 1
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MAPLE
| G := proc(n, k) if k=0 or n =k then 1; elif k= 1 then 2 ; elif k =2 then 4; elif k > n or k < 0 then 0 ; else procname(n-3, k-2)+procname(n-3, k-3)+procname(n-2, k-2)+procname(n-1, k-1) ; end if; end proc: seq(seq(G(n, k), k=0..n), n=0..15) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 14 2010]
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CROSSREFS
| Cf. A007318.
Sequence in context: A023506 A140995 A141021 * A140993 A027935 A137940
Adjacent sequences: A140991 A140992 A140993 * A140995 A140996 A140997
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KEYWORD
| nonn,tabl
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AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jul 08 2008
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EXTENSIONS
| Entries checked by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 14 2010
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