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Search: id:A111638
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| A111638 |
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Numbers having a unique partition into three positive triangular numbers. |
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+0
2
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| 3, 5, 7, 8, 9, 10, 13, 14, 15, 16, 18, 24, 25, 36, 38, 50, 53, 55, 60, 69, 81, 83, 99, 110, 119
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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Example: 119=55+36+28
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MATHEMATICA
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trig[n_]:=n(n+1)/2; trigInv[x_]:=Ceiling[Sqrt[Max[0, 2x]]]; lim=100; nLst=Table[0, {trig[lim]}]; Do[n=trig[a]+trig[b]+trig[c]; If[n>0 && n<=trig[lim], nLst[[n]]++ ], {a, 1, lim}, {b, a, trigInv[trig[lim]-trig[a]]}, {c, b, trigInv[trig[lim]-trig[a]-trig[b]]}]; Flatten[Position[nLst, 1]]
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CROSSREFS
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Cf. A060773 (n having a unique partition into three nonnegative triangular numbers).
Sequence in context: A136443 A020491 A047746 this_sequence A080262 A160238 A025050
Adjacent sequences: A111635 A111636 A111637 this_sequence A111639 A111640 A111641
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KEYWORD
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fini,full,nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Aug 10 2005
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