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 A001219 Triangular numbers of form a(a+1)(a+2). 7
 0, 6, 120, 210, 990, 185136, 258474216 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES R. K. Guy, Unsolved Problems in Number Theory, D3. LINKS S. P. Mohanty, Which triangular numbers are products of three consecutive integers?, Acta Mathematica Hungarica 1991, Volume 58, Issue 1-2, pp 31-36. Eric Weisstein's World of Mathematics, Triangular Number. FORMULA a(n) = A000217(A097571(n)). - Michel Marcus, Jan 14 2015 MAPLE count:= 0: for a from 0 to 637 do   p:= a*(a+1)*(a+2);   if issqr(1+8*p) then     count:= count+1;     A[count]:= p;   fi od: seq(A[i], i=1..count); # Robert Israel, Jan 14 2015 MATHEMATICA Select[Times @@@ Partition[Range[0, 700], 3, 1], OddQ[ Sqrt[ 8 # + 1]] &] (* Harvey P. Dale, Nov 04 2017 *) CROSSREFS Sequence in context: A117063 A178911 A227027 * A224303 A076233 A066581 Adjacent sequences:  A001216 A001217 A001218 * A001220 A001221 A001222 KEYWORD nonn,fini,full AUTHOR STATUS approved

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Last modified December 14 09:20 EST 2018. Contains 318091 sequences. (Running on oeis4.)