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A058498 Number of solutions to c(1)t(1) + ... + c(n)t(n) = 0, where c(i) = +-1 for i>1, c(1) = t(1) = 1, t(i) = triangular numbers (A000217). 7
0, 0, 0, 1, 0, 1, 1, 2, 0, 6, 8, 13, 0, 33, 52, 105, 0, 310, 485, 874, 0, 2974, 5240, 9488, 0, 30418, 55715, 104730, 0, 352467, 642418, 1193879, 0, 4165910, 7762907, 14493951, 0, 50621491, 95133799, 179484713, 0, 637516130, 1202062094, 2273709847, 0, 8173584069 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

LINKS

Alois P. Heinz and Ray Chandler, Table of n, a(n) for n = 1..633 (first 280 terms from Alois P. Heinz)

EXAMPLE

a(8) = 2 because there are two solutions: 1 - 3 + 6 + 10 + 15 - 21 + 28 - 36 = 1 - 3 - 6 + 10 - 15 + 21 + 28 - 36 = 0.

MAPLE

b:= proc(n, i) option remember; local m; m:= (2+(3+i)*i)*i/6;

      `if`(n>m, 0, `if`(n=m, 1,

      b(abs(n-i*(i+1)/2), i-1) +b(n+i*(i+1)/2, i-1)))

    end:

a:= n-> `if`(irem(n, 4)=1, 0, b(n*(n+1)/2, n-1)):

seq(a(n), n=1..40);  # Alois P. Heinz, Oct 31 2011

MATHEMATICA

b[n_, i_] := b[n, i] = With[{m = (2+(3+i)*i)*i/6}, If[n>m, 0, If[n == m, 1, b[Abs[n - i*(i+1)/2], i-1] + b[n + i*(i+1)/2, i-1]]]]; a[n_] := If[Mod[n, 4] == 1, 0, b[n*(n+1)/2, n-1]]; Table[a[n], {n, 1, 40}] (* Jean-Fran├žois Alcover, Jan 30 2017, after Alois P. Heinz *)

CROSSREFS

Cf. A000217.

Sequence in context: A248507 A087996 A086777 * A003076 A175478 A011123

Adjacent sequences:  A058495 A058496 A058497 * A058499 A058500 A058501

KEYWORD

nonn

AUTHOR

Naohiro Nomoto, Dec 20 2000

EXTENSIONS

More terms from Sascha Kurz, Oct 13 2001

More terms from Alois P. Heinz, Oct 31 2011

STATUS

approved

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Last modified November 20 13:03 EST 2019. Contains 329336 sequences. (Running on oeis4.)