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A326414 Numbers which require exactly 288 'Reverse and Add' steps to reach a palindrome. 1
12000700000025339936491, 12000700001015339936491, 12000700002005339936491, 12000700010024339936491, 12000700011014339936491, 12000700012004339936491, 12000700020023339936491, 12000700021013339936491, 12000700022003339936491, 12000700030022339936491 (list; graph; refs; listen; history; text; internal format)



The sequence starts with 12000700000025339936491 (the number discovered by Rob van Nobelen on April 26, 2019), ends with 29463993352000000700020 and contains 19353600 terms known at present.


Popular Computing (Calabasas, CA), The 196 Problem, Vol. 3 (No. 30, Sep 1975).


Sergei D. Shchebetov, Table of n, a(n) for n = 1..10000

Jason Doucette, World Records

Yutaka Nishiyama, Numerical Palindromes and the 196 Problem, International Journal of Pure and Applied Mathematics, Volume 80, No. 3, 2012, 375-384.

Sergei D. Shchebetov, 19353600 terms (zipped file)

R. Styer, The Palindromic Conjecture and the Fibonacci Sequence, Villanova University, 1986, 1-11.

C. W. Trigg, Palindromes by Addition, Mathematics Magazine, 40 (1967), 26-28.

C. W. Trigg, More on Palindromes by Reversal-Addition, Mathematics Magazine, 45 (1972), 184-186.

Wikipedia, Lychrel Number

196 and Other Lychrel Numbers, 196 and Lychrel Number

Index entries for sequences related to Reverse and Add!


Each term requires exactly 288 steps to turn into a 142-digit palindrome.


Cf. A023109, A033672, A065198, A065199, A065320, A065321, A065322, A065323, A065324, A065325, A065326, A065327, A070743, A072216, A072217, A072218, A281301, A281390, A281506, A281507.

Sequence in context: A171265 A180247 A095440 * A162033 A246254 A238360

Adjacent sequences:  A326411 A326412 A326413 * A326415 A326416 A326417




Andrey S. Shchebetov and Sergei D. Shchebetov, Oct 18 2019



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Last modified December 10 20:23 EST 2019. Contains 329909 sequences. (Running on oeis4.)