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 A028555 Numbers n such that n*(n + 4) is a palindrome. 0
 0, 1, 7, 14, 21, 33, 44, 144, 235, 269, 524, 1123, 1452, 1582, 5412, 8338, 8459, 11063, 11223, 23255, 73491, 145544, 262808, 266737, 281349, 1659022, 2705669, 3504083, 5040882, 7395091, 8308388, 14554452 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Patrick De Geest, Palindromic Quasipronics of the form n(n+x) Erich Friedman, What's Special About This Number? (See entries 1452, 1582, 5412, 8338, 8459.) MATHEMATICA Select[Range[0, 9999], PalindromeQ[#^2 + 4#] &] (* 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 + 4 * n)) // Alonso del Arte, Nov 10 2019 CROSSREFS Cf. A028336. Sequence in context: A189931 A164005 A100451 * A061823 A018890 A118502 Adjacent sequences:  A028552 A028553 A028554 * A028556 A028557 A028558 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified January 21 05:39 EST 2020. Contains 331104 sequences. (Running on oeis4.)