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A058498
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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).
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5
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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; internal format)
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OFFSET
| 1,8
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LINKS
| Alois P. Heinz, Table of n, a(n) for n = 1..280
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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.
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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
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CROSSREFS
| Cf. A000217.
Sequence in context: A057720 A087996 A086777 * A003076 A175478 A011123
Adjacent sequences: A058495 A058496 A058497 * A058499 A058500 A058501
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KEYWORD
| nonn
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AUTHOR
| Naohiro Nomoto (6284968128(AT)geocities.co.jp), Dec 20 2000
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EXTENSIONS
| More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Oct 13 2001
More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), Oct 31 2011
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