A179889 Triangular numbers whose reverse is a square (possibly with fewer digits).

1, 10, 630, 52650, 165600, 986310, 9446031, 9485190, 10693000, 1270004401, 14214075921, 140884670790, 1809702709101, 4614899724711, 6766532724546, 9802814901400, 10210140486640, 14287075542460, 52657436563056, 98855178542676

Offset

1,2

Links

Giovanni Resta, Table of n, a(n) for n = 1..36 (terms < 2*10^24)

Example

9446031 is triangular and 1306449 is a square.

Mathematica

trnos=Accumulate[Range[14070000]];
sqnoQ[n_]:=IntegerQ[Sqrt[FromDigits[Reverse[IntegerDigits[n]]]]]
Select[trnos, sqnoQ]  (* Harvey P. Dale, Jan 31 2011 *)

Crossrefs

A variant of A066703. Cf. A069673, A181412, A066528.

Sequence in context: A308145 A159622 A115692 * A209472 A132543 A261328

Adjacent sequences: A179886 A179887 A179888 * A179890 A179891 A179892

Keyword

base,nonn

Author

Harvey P. Dale, Jan 30 2011

Extensions

More terms from Harvey P. Dale, Jan 31 2011

Status

approved