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A002069 Palindromic pentagonal numbers.
(Formerly M3924 N1612)
5

%I M3924 N1612 #25 Dec 23 2021 22:44:48

%S 0,1,5,22,1001,2882,15251,720027,7081807,7451547,26811862,54177145,

%T 1050660501,1085885801,1528888251,2911771192,2376574756732,

%U 5792526252975,5875432345785,10810300301801,264571020175462,5292834004382925,10808388588380801,15017579397571051

%N Palindromic pentagonal numbers.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Robert Price, <a href="/A002069/b002069.txt">Table of n, a(n) for n = 1..30</a>

%H P. De Geest, <a href="http://www.worldofnumbers.com/penta.htm">More about Palindromic Pentagonals</a>

%H A. Gloden and R. A. Johnson, <a href="http://www.jstor.org/stable/2304262">Problem E427</a>, Amer. Math. Monthly, 48 (1941), 211-212.

%t Select[PolygonalNumber[5,Range[0,6*10^7]],PalindromeQ] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jan 15 2018 *)

%Y Cf. A028386, A000326.

%K nonn,base

%O 1,3

%A _N. J. A. Sloane_

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Last modified March 29 08:13 EDT 2024. Contains 371265 sequences. (Running on oeis4.)