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A160466 Row sums of the Eta triangle A160464 6
-1, -9, -87, -2925, -75870, -2811375, -141027075, -18407924325, -1516052821500, -153801543183750, -18845978136851250, -2744283682352086875, -468435979952504313750, -92643070481933918821875 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

It is conjectured that the row sums of the Eta triangle depend on five different sequences.

Two Maple algorithms are given. The first one gives the row sums according to the Eta triangle A160464 and the second one gives the row sums according to our conjecture.

LINKS

Table of n, a(n) for n=2..15.

FORMULA

Rowsums(n) = (-1) * A119951(n-1) * FF(n) for n >= 2.

FF(n) = SF(n) * FF(n-1) for n >= 3 with FF(2) =1.

SF(2*n) = A045896(n-2) / A160467(n) for n >= 2.

SF(2*n+1) = A000466(n) / A043529(n-1) for n >= 1.

MAPLE

nmax:=15; c(2) := -1/3: for n from 3 to nmax do c(n):=(2*n-2)*c(n-1)/(2*n-1)-1/ ((n-1)*(2*n-1)) end do: for n from 2 to nmax do GCS(n-1) := ln(1/(2^(-(2*(n-1)-1-floor(ln(n-1)/ ln(2))))))/ln(2); p(n):=2^(-GCS(n-1))*(2*n-1)!; ETA(n, 1) := p(n)*c(n) end do: mmax:=nmax: for m from 2 to mmax do ETA(2, m) := 0 end do: for n from 3 to nmax do for m from 2 to mmax do q(n) := (1+(-1)^(n-3)*(floor(ln(n-1)/ln(2)) - floor(ln(n-2)/ln(2)))): ETA(n, m) := q(n)*(-ETA(n-1, m-1)+(n-1)^2*ETA(n-1, m)) end do end do: for n from 2 to nmax do s1(n):=0: for m from 1 to n-1 do s1(n) := s1(n) + ETA(n, m) end do end do: seq(s1(n), n=2..nmax);

# End first program.

nmax:=nmax; A160467 := proc(n): denom(4*(4^n-1)*bernoulli(2*n)/n) end: A043529 := proc(n): ceil(frac(log[2](n+1))+1) end proc: A000466 := proc(n): 4*n^2-1 end proc: A045896 := proc(n): denom((n)/((n+1)*(n+2))) end proc: A119951 := proc(n) : numer(sum(((2*k1)!/(k1!*(k1+1)!))/2^(2*(k1-1)), k1=1..n)) end proc: for n from 1 to nmax do SF(2*n+1):= A000466(n)/A043529(n-1); SF(2*n+2) := A045896(n-1)/A160467(n+1) end do: FF(2):=1: for n from 3 to nmax do FF(n) := SF(n) * FF(n-1) end do: for n from 2 to nmax do s2(n):= (-1)*A119951(n-1)*FF(n) end do: seq(s2(n), n=2..nmax);

# End second program.

CROSSREFS

A160464 is the Eta triangle.

Row sum factors A119951, A000466, A043529, A045896 and A160467.

Sequence in context: A152264 A035101 A245491 * A015583 A152266 A260041

Adjacent sequences:  A160463 A160464 A160465 * A160467 A160468 A160469

KEYWORD

easy,sign

AUTHOR

Johannes W. Meijer, May 24 2009

STATUS

approved

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Last modified November 20 23:06 EST 2019. Contains 329348 sequences. (Running on oeis4.)