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A229701 Squares of triangular numbers, written backwards. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A081574 A084151 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

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Last modified May 11 07:29 EDT 2021. Contains 343784 sequences. (Running on oeis4.)