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 A278257 Least number with the prime signature of A005187(n). 1
 1, 2, 4, 2, 8, 6, 2, 6, 16, 12, 2, 6, 2, 4, 6, 2, 32, 6, 6, 6, 6, 2, 30, 6, 2, 4, 12, 2, 24, 24, 6, 12, 64, 30, 2, 30, 2, 2, 6, 30, 2, 16, 6, 6, 6, 24, 2, 6, 6, 2, 12, 2, 30, 24, 30, 2, 30, 48, 2, 12, 12, 6, 120, 2, 128, 30, 2, 6, 24, 2, 30, 6, 6, 6, 6, 2, 60, 24, 12, 6, 6, 6, 48, 30, 6, 120, 4, 2, 30, 48, 6, 180, 2, 6, 24, 30, 2, 2, 6, 2, 60, 72, 6, 6, 6, 48 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Antti Karttunen, Table of n, a(n) for n = 1..8193 FORMULA a(n) = A046523(A005187(n)). MATHEMATICA f[n_] := If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Sort@ #[[All, -1]]] &@ FactorInteger@ n; Table[k = 1; While[f@ k != #, k++] &@ f[2 n - DigitCount[2 n, 2, 1]]; k, {n, 106}] (* or, faster *) Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length# == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[2 n - DigitCount[2 n, 2, 1]], {n, 106}] (* Michael De Vlieger, Nov 21 2016 *) PROG (Scheme) (define (A278257 n) (A046523 (A005187 n))) CROSSREFS Cf A005187, A046523. Sequence in context: A174147 A163897 A278541 * A278533 A204898 A240295 Adjacent sequences:  A278254 A278255 A278256 * A278258 A278259 A278260 KEYWORD nonn AUTHOR Antti Karttunen, Nov 19 2016 STATUS approved

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Last modified August 3 22:03 EDT 2021. Contains 346441 sequences. (Running on oeis4.)