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 A225538 Let r(n) denote the reverse of n. For every n, consider the sequence n_1 = n + 1 + r(n+1), and for m >= 2, n_m = n_(m-1) + 1 + r(n_(m-1) + 1). a(n) is the least m for which n_m is a palindrome, or 0 if there is no such m. 1
 1, 1, 1, 1, 2, 2, 2, 2, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 1, 1, 2, 1, 2, 2, 4, 1, 1, 1, 1, 2, 1, 2, 2, 4, 7, 1, 1, 1, 2, 1, 2, 2, 4, 7, 10, 1, 1, 2, 1, 2, 2, 4, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Conjecture: the least n's for which a(n) = 0 are 1895, 1985, 2894, 2984, 3893, and 3983. - Peter J. C. Moses, May 10 2013 See analogous numbers in A023108 for which the so-called Lychrel process "Reverse and Add!", apparently, never leads to a palindrome. LINKS Peter J. C. Moses, Table of n, a(n) for n = 0..5000 EXAMPLE For n=8, 9 + 9 = 18, 19 + 91 = 110, 111 + 111 = 222 is a palindrome. Thus a(8)=3. CROSSREFS Cf. A023108. Sequence in context: A343121 A090872 A283472 * A212355 A238646 A194330 Adjacent sequences:  A225535 A225536 A225537 * A225539 A225540 A225541 KEYWORD nonn,base AUTHOR Vladimir Shevelev, May 10 2013 STATUS approved

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Last modified December 6 01:25 EST 2021. Contains 349558 sequences. (Running on oeis4.)