A115678 Triangular numbers whose digit reversal is a brilliant number (A078972).

6, 120, 946, 1540, 7021, 13366, 14365, 15400, 19306, 35245, 72010, 95266, 156520, 179101, 191890, 334153, 341551, 913276, 925480, 933661, 946000, 1008910, 1030330, 1131760, 1383616, 1945378, 3066526, 3156328, 3308878, 3584503

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1001 [Additional term a(42)=10693000 inserted by Georg Fischer, Feb 28 2026]

Example

a(3) = 946 = A000217(43) and 649 = 11*59 is brilliant.
a(42) = 10693000 = A000217(4624) is triangular and semiprime A001358(9697) = 39601 = 199^2 = A078972(718) is brilliant.

Mathematica

bnoQ[n_]:=With[{fi=FactorInteger[IntegerReverse[n]][[;; , 1]]}, PrimeOmega[IntegerReverse[n]]==2&&(Length[fi]==1||IntegerLength[fi[[1]]]==IntegerLength[fi[[2]]])]; Select[Accumulate[Range[10000]], bnoQ] (* Harvey P. Dale, Feb 28 2026 *)

Crossrefs

Cf. A078972, A115677.

Sequence in context: A066289 A351862 A170917 * A048604 A001516 A350712

Adjacent sequences: A115675 A115676 A115677 * A115679 A115680 A115681

Keyword

nonn,base

Author

Giovanni Resta, Jan 31 2006

Status

approved