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 A286605 Restricted growth sequence computed for number of divisors, d(n) (A000005). 9
 1, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 5, 2, 4, 4, 6, 2, 5, 2, 5, 4, 4, 2, 7, 3, 4, 4, 5, 2, 7, 2, 5, 4, 4, 4, 8, 2, 4, 4, 7, 2, 7, 2, 5, 5, 4, 2, 9, 3, 5, 4, 5, 2, 7, 4, 7, 4, 4, 2, 10, 2, 4, 5, 11, 4, 7, 2, 5, 4, 7, 2, 10, 2, 4, 5, 5, 4, 7, 2, 9, 6, 4, 2, 10, 4, 4, 4, 7, 2, 10, 4, 5, 4, 4, 4, 10, 2, 5, 5, 8, 2, 7, 2, 7, 7, 4, 2, 10, 2, 7, 4, 9, 2, 7, 4, 5, 5, 4, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For all i, j: A101296(i) = A101296(j) => a(i) = a(j). For all i, j: a(i) = a(j) <=> A000005(i) = A000005(j). LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 MATHEMATICA With[{nn = 119}, Function[s, Table[Position[Keys@ s, k_ /; MemberQ[k, n]][[1, 1]], {n, nn}]]@ Map[#1 -> #2 & @@ # &, Transpose@ {Values@ #, Keys@ #}] &@ PositionIndex@ Array[DivisorSigma[0, #] &, nn]] (* Michael De Vlieger, May 12 2017, Version 10 *) PROG (PARI) rgs_transform(invec) = { my(occurrences = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(occurrences, invec[i]), my(pp = mapget(occurrences, invec[i])); outvec[i] = outvec[pp] , mapput(occurrences, invec[i], i); outvec[i] = u; u++ )); outvec; }; write_to_bfile(start_offset, vec, bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); } A000005(n) = numdiv(n); write_to_bfile(1, rgs_transform(vector(10000, n, A000005(n))), "b286605.txt"); CROSSREFS Cf. A000005, A007416 (positions of records, and also the first occurrence of each n). Cf. also A101296, A286603, A286610, A286619, A286621, A286622, A286626, A286378. Sequence in context: A337454 A289849 A299701 * A035149 A074848 A252505 Adjacent sequences:  A286602 A286603 A286604 * A286606 A286607 A286608 KEYWORD nonn AUTHOR Antti Karttunen, May 11 2017 STATUS approved

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Last modified November 28 22:01 EST 2021. Contains 349415 sequences. (Running on oeis4.)