A229701 Squares of triangular numbers, written backwards.

1, 9, 63, 1, 522, 144, 487, 6921, 5202, 5203, 6534, 4806, 1828, 52011, 441, 69481, 90432, 14292, 163, 144, 16335, 90046, 67167, 9, 526501, 102321, 488241, 638461, 522981, 522612, 610642, 487872, 127413, 520453, 9693, 655344, 902494, 180945, 4806, 4276, 123147

Offset

1,2

Links

K. D. Bajpai, Table of n, a(n) for n = 1..1000

Formula

n-th triangular number = T(n) = n*(n+1)/2.

Example

a(3) = 63: T(3) = 3/2*(3+1) = 6 and 6^2 = 36. Writing it backwards gives 63.
a(6) = 144: T(6) = 6/2*(6+1) = 21 and 21^2 = 441. Writing it backwards gives 144.

Maple

with(StringTools):KD:= proc() local a; a:= parse(Reverse(convert(((n/2*(n+1))^2), string))); RETURN (a): end: seq(KD(), n=1..100);

Mathematica

Table[FromDigits[Reverse[IntegerDigits[(n*(n + 1)/2)^2]]], {n, 1, 100}]

Crossrefs

Cf. A004158.

Sequence in context: A084151 A346396 A240391 * A341627 A159235 A181403

Adjacent sequences: A229698 A229699 A229700 * A229702 A229703 A229704

Keyword

nonn,base,less

Author

K. D. Bajpai, Sep 27 2013

Status

approved