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A162703 Palindromes in A005448. 1
1, 4, 15151, 45154, 66466, 92629, 98689, 4976794, 6424246, 648616846, 136287949782631, 479573060375974, 69465717171756496, 4345218593958125434, 42097537753535773579024, 58071646151315164617085, 6220959179720279719590226 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Essentially the palindromes which are sums of three consecutive triangular numbers T.

Indices of the centered triangular numbers: 1, 2, 101, 174, 211, 249, 257, 1822, 2070, 20795, 9531980, 17880587, 215198695, ..., . - Robert G. Wilson v

a(18) > 10^25. - Donovan Johnson, Sep 29 2011

LINKS

Table of n, a(n) for n=1..17.

EXAMPLE

T(99) + T(100) + T(101) = 15151.

T(172) + T(173) + T(174) = 45154.

MATHEMATICA

n = 1; lst = {}; While[n < 10^10, ctn = 3 n (n - 1)/2 + 1; id = IntegerDigits@ ctn; If[id == Reverse@id, AppendTo[lst, ctn]; Print[{n, ctn}]]; n++ ]; lst (* Robert G. Wilson v *)

CROSSREFS

Cf. A005448, A000217.

Sequence in context: A134368 A152840 A003832 * A258101 A265215 A070157

Adjacent sequences:  A162700 A162701 A162702 * A162704 A162705 A162706

KEYWORD

nonn,base

AUTHOR

Claudio Meller, Jul 11 2009

EXTENSIONS

Edited and extended by R. J. Mathar and Robert G. Wilson v, Jul 13 2009

a(14)-a(17) from Donovan Johnson, Sep 29 2011

STATUS

approved

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Last modified September 20 18:52 EDT 2019. Contains 327245 sequences. (Running on oeis4.)