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A028570 Numbers n such that n(n + 9) is a palindrome. 0
0, 2, 12, 44, 137, 157, 167, 248, 258, 1639, 1664, 1694, 5392, 15904, 16997, 160187, 487619, 1547147, 14674184, 14790532, 15019614, 15336644, 25234083, 26132578, 26211438, 26216753 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..26.

Patrick De Geest, Palindromic Quasipronics of the form n(n+x)

Erich Friedman, What's Special About This Number? (See entries 258, 1664.)

MATHEMATICA

Select[Range[0, 9999], PalindromeQ[#^2 + 9#] &] (* Alonso del Arte, Nov 10 2019 *)

PROG

(Scala) def palQ(n: Int, b: Int = 10): Boolean = n - Integer.parseInt(n.toString.reverse) == 0

(0 to 9999).filter((n: Int) => palQ(n * n + 9 * n)) // Alonso del Arte, Nov 10 2019

(MAGMA) f:=func<n| Intseq(n) eq Reverse(Intseq(n))>; [k:k in [0..2*10^7]| f(k*(k+9))]; // Marius A. Burtea, Nov 11 2019

CROSSREFS

Cf. A028569, A028571.

Sequence in context: A203278 A013704 A025495 * A009074 A267344 A275132

Adjacent sequences:  A028567 A028568 A028569 * A028571 A028572 A028573

KEYWORD

nonn,base,easy

AUTHOR

Patrick De Geest

STATUS

approved

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Last modified April 12 18:58 EDT 2021. Contains 342932 sequences. (Running on oeis4.)