A034291 Triangular numbers that have some nontrivial permutation of digits which is also triangular.

120, 153, 210, 253, 325, 351, 496, 946, 1378, 1485, 1830, 1891, 2145, 2415, 2701, 3081, 3570, 3655, 3741, 3916, 4095, 4371, 4560, 4851, 4950, 5356, 5460, 5565, 5778, 6555, 7021, 7381, 7503, 7875, 8911, 9045, 9316, 10296, 11325, 11476, 11935, 12090

Offset

1,1

Links

Table of n, a(n) for n=1..42.

Mathematica

tnpQ[n_]:=Module[{p=FromDigits/@Rest[Permutations[IntegerDigits[n]]], q}, q= DeleteCases[ p, _?(IntegerLength[#]!=IntegerLength[n]&)]; Count[q, _?(OddQ[ Sqrt[8#+1]]&)]>0]; Select[Accumulate[Range[200]], tnpQ]

Crossrefs

Cf. A000217.

Sequence in context: A248662 A259826 A192277 * A039602 A316835 A179642

Adjacent sequences: A034288 A034289 A034290 * A034292 A034293 A034294

Keyword

nonn,base

Author

Erich Friedman

Extensions

Offset set to 1 by Sean A. Irvine, Aug 20 2020

Status

approved