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 A055483 a(n) is the GCD of n and the reverse of n. 21
 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 11, 3, 1, 1, 3, 1, 1, 9, 1, 2, 3, 22, 1, 6, 1, 2, 9, 2, 1, 3, 1, 1, 33, 1, 1, 9, 1, 1, 3, 4, 1, 6, 1, 44, 9, 2, 1, 12, 1, 5, 3, 1, 1, 9, 55, 1, 3, 1, 1, 6, 1, 2, 9, 2, 1, 66, 1, 2, 3, 7, 1, 9, 1, 1, 3, 1, 77, 3, 1, 8, 9, 2, 1, 12, 1, 2, 3, 88, 1, 9, 1, 1, 3, 1, 1, 3, 1, 1, 99, 1, 101, 3, 1, 1, 3, 1, 1, 9, 1, 11, 111 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(A226778(n)) = 1; a(A071249(n)) > 1. - Reinhard Zumkeller, Jun 18 2013 a(n) = n iff n >= 1 is a palindrome (n is in A002113). - Felix Fröhlich, Oct 28 2014 LINKS Indranil Ghosh, Table of n, a(n) for n = 1..50000 (first 1000 terms from T. D. Noe) FORMULA a(n) = gcd(n, A004086(n)). - Felix Fröhlich, Oct 28 2014 3 | a(n) if 3 | n and 9 | a(n) if 9 | n. - Alonso del Arte, Aug 31 2021 EXAMPLE a(12) = 3 since gcd(12, 21) = 3. a(13) = 1 since 13 and 31 are coprime. a(101) = gcd(101, 101) = 101. MATHEMATICA gcn[n_] := GCD[n, IntegerReverse[n]]; Array[gcn, 120] (* Harvey P. Dale, Jan 23 2012 *) PROG (Haskell) a055483 n = gcd n \$ a004086 n -- Reinhard Zumkeller, Jun 18 2013 (PARI) a004086(n)=eval(concat(Vecrev(Str(n)))) a(n)=gcd(n, a004086(n)) \\ Felix Fröhlich, Oct 28 2014 (Magma) [Gcd(n, Seqint(Reverse(Intseq(n)))): n in [1..100]]; // Vincenzo Librandi, Oct 29 2014 (Scala) def reverseDigits(n: Int): Int = Integer.parseInt(n.toString.reverse) def euclGCD(a: Int, b: Int): Int = b match { case 0 => a; case n => Math.abs(euclGCD(b, a % b)) } (1 to 120).map(n => euclGCD(n, reverseDigits(n))) // Alonso del Arte, Aug 31 2021 (Python) from math import gcd def a(n): return gcd(n, int(str(n)[::-1])) print([a(n) for n in range(1, 112)]) # Michael S. Branicky, Aug 31 2021 CROSSREFS Different from A069652, first differs at a(101), since gcd(101, 110) = 1. Cf. A002113, A004086, A071249, A226778. Sequence in context: A047813 A084051 A069652 * A331472 A364362 A059717 Adjacent sequences: A055480 A055481 A055482 * A055484 A055485 A055486 KEYWORD base,easy,nonn,nice,changed AUTHOR Erich Friedman, Jun 27 2000 EXTENSIONS Edited by Robert G. Wilson v, Apr 10 2002 STATUS approved

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Last modified March 2 08:43 EST 2024. Contains 370461 sequences. (Running on oeis4.)