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Search: id:A002775
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| A002775 |
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n^2*n!.
(Formerly M4540 N1927)
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+0
4
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| 0, 1, 8, 54, 384, 3000, 25920, 246960, 2580480, 29393280, 362880000, 4829932800, 68976230400, 1052366515200, 17086945075200, 294226732800000, 5356234211328000, 102793666719744000, 2074369080655872000, 43913881247588352000, 973160803270656000000, 22531105497723863040000
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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J. D. H. Dickson, Discussion of two double series arising from the number of terms in determinants of certain forms, Proc. London Math. Soc., 10 (1879), 120-122.
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FORMULA
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E.g.f.: x*(1+x)/(1-x)^3. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Dec 01 2002
Sum of all matrix elements M(i, j) = i/(i+j) multiplied by 2*n!. a(n) = 2*n! * Sum[Sum[i/(i+j), {i, 1, n}], {j, 1, n}] Example: a(2) = 2*2! * (1/(1+1) + 1/(1+2) + 2/(2+1) + 2/(2+2)) = 8 - Alexander Adamchuk (alex(AT)kolmogorov.com), Oct 24 2004
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MAPLE
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with(combinat):for n from 0 to 15 do printf(`%d, `, n!/2*sum(2*n, k=1..n)) od: - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 13 2007
seq(sum(sum(mul(k, k=1..n), l=1..n), m=1..n), n=0..21); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 26 2008
with (combstruct):a:=proc(m) [ZL, {ZL=Set(Cycle(Z, card>=m))}, labeled]; end: ZLL:=a(1):seq(count(ZLL, size=n)*n^2, n=0..21); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 11 2008
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CROSSREFS
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Cf. A047922.
Sequence in context: A091433 A081899 A057970 this_sequence A079754 A138403 A013499
Adjacent sequences: A002772 A002773 A002774 this_sequence A002776 A002777 A002778
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KEYWORD
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nonn
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AUTHOR
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njas
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