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 A182594 Number of prime factors of form cn+1 for numbers 7^n-1 0
 1, 1, 2, 1, 2, 2, 1, 3, 3, 2, 2, 1, 4, 2, 3, 2, 4, 2, 3, 1, 4, 3, 4, 3, 3, 4, 4, 3, 3, 3, 2, 4, 3, 3, 3, 3, 4, 4, 5, 3, 4, 2, 4, 2, 4, 2, 3, 4, 4, 5, 5, 3, 5, 1, 6, 3, 4, 4, 5, 4, 6, 2, 3, 6, 6, 4, 6, 3, 8, 2, 5, 5, 5, 3, 2, 3, 7, 2, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,3 LINKS Table of n, a(n) for n=2..80. S. Mustonen, On prime factors of numbers m^n+-1 Seppo Mustonen, On prime factors of numbers m^n+-1 [Local copy] EXAMPLE For n=9, 7^n-1=40353606=2*3^3*19*37*1063 has three prime factors of form, namely 19=2n+1, 37=6n+1, 1063=118n+1. Thus a(9)=3. MATHEMATICA m = 7; n = 2; nmax = 80; While[n <= nmax, {l = FactorInteger[m^n - 1]; s = 0; For[i = 1, i <= Length[l], i++, {p = l[[i, 1]]; If[IntegerQ[(p - 1)/n] == True, s = s + l[[i, 2]]]; }]; a[n] = s; } n++; ]; Table[a[n], {n, 2, nmax}] CROSSREFS Sequence in context: A276430 A362325 A325002 * A201593 A029287 A055184 Adjacent sequences: A182591 A182592 A182593 * A182595 A182596 A182597 KEYWORD nonn AUTHOR Seppo Mustonen, Nov 22 2010 STATUS approved

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Last modified September 23 04:30 EDT 2023. Contains 365532 sequences. (Running on oeis4.)