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A114646
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Let M(n) be the n X n matrix m(i,j)=min(i,j) for 1<=i,j<=n then a(n) is the trace of M(n)^(-4).
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3
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1, 47, 117, 187, 257, 327, 397, 467, 537, 607, 677, 747, 817, 887, 957, 1027, 1097, 1167, 1237, 1307, 1377, 1447, 1517, 1587, 1657, 1727, 1797, 1867, 1937, 2007, 2077, 2147, 2217, 2287, 2357, 2427, 2497, 2567, 2637, 2707, 2777, 2847, 2917, 2987, 3057
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| More generally for any n>=floor((m+1)/2) the trace of M(n)^(-m) = binomial(2*m,m)*n-2^(2*m-1)+binomial(2*m-1,m)
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FORMULA
| a(1)=1 then a(n)=70n-93
(Conjecture) G.f.: F(x)=x*(1+45*x+24*x^2)/(1-x)^2. - L. Edson Jeffery, Jan 21 2012
(Conjecture) a(n)=2*a(n-1)-a(n-2), n>1, a(1)=1, a(2)=47. - L. Edson Jeffery, Jan 21 2012
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PROG
| (PARI) a(n)=if(n<2, 1, 70*n-93)
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CROSSREFS
| Sequence in context: A044234 A044615 A142057 * A118091 A044298 A044679
Adjacent sequences: A114643 A114644 A114645 * A114647 A114648 A114649
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Feb 09 2006
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