A066702 Square numbers whose reverse is triangular with the same number of digits.

0, 1, 1306449, 1044000721, 12957041241, 1019072079081, 1174279984164, 6454272356676, 65036563475625, 67624587155889, 123826990849454025, 170448128872993657764, 19198191503444720114404

Offset

1,3

Comments

The sequence of corresponding triangular numbers is A066703. - Robert G. Wilson v, Jan 31 2011

Links

Table of n, a(n) for n=1..13.

Example

9446031 is triangular and 1306449 is a square.

Mathematica

lst = {0}; For[i = 1, i > 0, i++, s = i^2; t = FromDigits@ Reverse@ IntegerDigits@ s; If[ IntegerQ@ Sqrt[8 t + 1] && Mod[s, 10] > 0, AppendTo[lst, s]; Print@ lst]]

Crossrefs

Cf. A066703, A181412. - Harvey P. Dale, Jan 30 2011

Sequence in context: A254187 A253799 A186138 * A261731 A141592 A234710

Adjacent sequences: A066699 A066700 A066701 * A066703 A066704 A066705

Keyword

base,more,nonn

Author

Erich Friedman, Jan 14 2002

Extensions

a(12)-a(13) from and offset corrected by Giovanni Resta, Jun 20 2015

Status

approved