A179889 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

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