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A115647 Triangular numbers that are sums of distinct factorials. 2
1, 3, 6, 120, 153, 5886, 40470, 41041, 40279800 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Factorials 0! and 1! are not considered distinct.
A115944(a(n)) > 0; subsequence of A059590. - Reinhard Zumkeller, Feb 02 2006
If there are any terms beyond 40279800 they must be larger than 48!. - Jon E. Schoenfield, Aug 04 2006
LINKS
EXAMPLE
1 = T(1) = 1!.
3 = T(2) = 2!+1!.
6 = T(3) = 3!.
120 = T(15) = 5!.
153 = T(17) = 5!+4!+3!+2!+1!.
5886 = T(108) = 7!+6!+5!+3!.
40470 = T(284) = 8!+5!+4!+3!.
41041 = T(286) = 8!+6!+1!.
40279800 = T(8975) = 11!+9!+5!.
MATHEMATICA
triQ[n_] := IntegerQ@Sqrt[8n+1]; fac=Reverse@Range[21]!; lst={}; Do[ n = Plus@@(fac*IntegerDigits[k, 2, 21]); If[triQ[n], AppendTo[lst, n]; Print[{n, k}]], {k, 2^21-1}]; Union@lst
CROSSREFS
Cf. A025494.
Sequence in context: A046488 A074880 A225884 * A019437 A365505 A291982
KEYWORD
nonn
AUTHOR
Giovanni Resta, Jan 27 2006
STATUS
approved

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Last modified February 21 03:46 EST 2024. Contains 370219 sequences. (Running on oeis4.)