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 A028336 Positive numbers k such that k*(k+1) is a palindrome. 3
 1, 2, 16, 77, 538, 1621, 2457, 5291, 5313, 52008, 142401, 143498, 1610151, 1713543, 4670028, 5218983, 15137566, 15282411, 15814148, 47370058, 50702751, 142594226, 166691108, 1694576061, 2554554552, 25541432472, 47878213558, 77714915542, 155482156418 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For additional terms, see the De Geest link. LINKS P. De Geest, Palindromic pronic numbers of the form n(n+1) Eric Weisstein's World of Mathematics, Palindromic Number. Eric Weisstein's World of Mathematics, Pronic Number. MATHEMATICA Select[Range[500000], PalindromeQ[#(#+1)] &] (* or *) Select[Range[50000], IntegerDigits[#(#+1)] == Reverse[ IntegerDigits[#(#+1)]] &] (* G. C. Greubel, Nov 24 2016 *) PROG (PARI) isok(k) = my(d = digits(k*(k+1))); Vecrev(d) == d; \\ Michel Marcus, Nov 09 2017 CROSSREFS Cf. A008509, A028337. Sequence in context: A289837 A323297 A034581 * A244717 A208102 A207723 Adjacent sequences:  A028333 A028334 A028335 * A028337 A028338 A028339 KEYWORD nonn,base AUTHOR EXTENSIONS More terms from Jon E. Schoenfield, Nov 09 2017 STATUS approved

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Last modified October 15 22:25 EDT 2019. Contains 328038 sequences. (Running on oeis4.)