

A195201


a(n) is the largest prime factor of the number made by taking the previous term and duplicating the final digit, a(1) = 1.


0



1, 11, 37, 29, 23, 233, 2333, 23333, 661, 601, 6011, 6679, 997, 907, 313, 241, 2411, 47, 53, 41, 137, 17, 59, 599, 857, 953, 9533, 13619, 19457, 821, 23, 233, 2333, 23333, 661, 601, 6011, 6679, 997, 907, 313, 241, 2411, 47, 53, 41, 137, 17, 59, 599, 857, 953
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OFFSET

1,2


COMMENTS

This sequence is periodic with period (23, 233, 2333, 23333, 661, 601, 6011, 6679, 997, 907, 313, 241, 2411, 47, 53, 41, 137, 17, 59, 599, 857, 953, 9533, 13619, 19457, 821) of length 26.


LINKS

Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).


EXAMPLE

Next term after 11 is 37 because 111 = 3*37. Next term after 37 is 29 because 377 = 13*29. Next term after 821 is 23 because 8211 = 3*7*17*23.


MATHEMATICA

NestList[FactorInteger[10#+Mod[#, 10]][[1, 1]]&, 11, 60](* Zak Seidov, Sep 16 2011*)


CROSSREFS



KEYWORD

nonn,base,easy


AUTHOR



EXTENSIONS



STATUS

approved



