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Search: id:A081908
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| 1, 2, 5, 14, 40, 112, 304, 800, 2048, 5120, 12544, 30208, 71680, 167936, 389120, 892928, 2031616, 4587520, 10289152, 22937600, 50855936, 112197632, 246415360, 538968064, 1174405120, 2550136832, 5519704064, 11911823360, 25635586048
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Binomial transform of A000124 (when this begins 1,1,2,4,7,...). 2nd binomial transform of (1,0,1,0,0,0,.....). Case k=2 where a(n,k)=k^n(n^2-n+2k^2)/(2k^2) with G.f. (1-2kx+(k^2+1)x^2)/(1-kx)^3
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FORMULA
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G.f.: (1-4x+5x^2)/(1-2x)^3
a(n)=A000079(n)+(A001788(n)-A001787(n))/2. - Paul Barry (pbarry(AT)wit.ie), May 27 2003
sum{k=0..n, C(n, k)(1+C(k, 2)) } - Paul Barry (pbarry(AT)wit.ie), May 27 2003
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CROSSREFS
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Cf. A081909.
Sequence in context: A126219 A111110 A111109 this_sequence A059505 A117189 A159035
Adjacent sequences: A081905 A081906 A081907 this_sequence A081909 A081910 A081911
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Mar 31 2003
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