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 A227071 Let s(m) = the set of k > 0 such that k^m ends with k. Then a(n) = least m such that s(m) = s(n). 2
 1, 2, 3, 2, 5, 6, 3, 2, 9, 2, 11, 2, 5, 2, 3, 6, 17, 2, 3, 2, 21, 2, 3, 2, 9, 26, 3, 2, 5, 2, 11, 2, 33, 2, 3, 6, 5, 2, 3, 2, 41, 2, 3, 2, 5, 6, 3, 2, 17, 2, 51, 2, 5, 2, 3, 6, 9, 2, 3, 2, 21, 2, 3, 2, 65, 6, 3, 2, 5, 2, 11, 2, 9, 2, 3, 26, 5, 2, 3, 2, 81, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS See A227070 for more details and for the numbers n such that n = a(n). The entries in the b-file have been tentatively obtained by comparing the terms < 10^30 in the sets s(n). - Giovanni Resta, Jul 30 2013 LINKS Giovanni Resta, Table of n, a(n) for n = 1..10000 FORMULA Conjecture: a(n+1) = A132741(n) + 1. - Eric M. Schmidt, Jul 30 2013 MATHEMATICA ts = {{}}; t2 = {1}; te = {1}; Do[s = Select[Range[0, 10^7], PowerMod[#, n, 10^IntegerLength[#]] == # &]; If[MemberQ[ts, s], AppendTo[t2, te[[Position[ts, s, 1, 1][[1, 1]]]]], AppendTo[ts, s]; AppendTo[te, n]; AppendTo[t2, n]], {n, 2, 82}]; t2 CROSSREFS Cf. A003226 (n=2), A033819 (n=3), A068407 (n=5), A068408 (n=6). Cf. A072496 (n=11), A072495 (n=21), A076650 (n=26). Cf. A227070 (n such that n = a(n)). Sequence in context: A066119 A003970 A094443 * A276270 A214571 A135873 Adjacent sequences:  A227068 A227069 A227070 * A227072 A227073 A227074 KEYWORD nonn,hard,base AUTHOR T. D. Noe, Jul 29 2013 EXTENSIONS Mma program and some entries corrected by Giovanni Resta, Jul 30 2013 STATUS approved

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Last modified September 23 07:26 EDT 2021. Contains 347609 sequences. (Running on oeis4.)