A323130 a(1) = 1, and for any n > 1, let p be the least prime factor of n, and e be its exponent, then a(n) = p^a(e).
1, 2, 3, 4, 5, 2, 7, 8, 9, 2, 11, 4, 13, 2, 3, 16, 17, 2, 19, 4, 3, 2, 23, 8, 25, 2, 27, 4, 29, 2, 31, 32, 3, 2, 5, 4, 37, 2, 3, 8, 41, 2, 43, 4, 9, 2, 47, 16, 49, 2, 3, 4, 53, 2, 5, 8, 3, 2, 59, 4, 61, 2, 9, 4, 5, 2, 67, 4, 3, 2, 71, 8, 73, 2, 3, 4, 7, 2, 79
Offset: 1
Keywords
Examples
a(320) = a(2^6 * 5) = 2^a(6) = 2^a(2*3) = 2^2 = 4.
Crossrefs
Programs
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Mathematica
Nest[Append[#, First@ FactorInteger[Length[#] + 1] /. {p_, e_} :> p^#[[e]] ] &, {1}, 78] (* Michael De Vlieger, Jan 07 2019 *) -
PARI
a(n) = if (n==1, 1, my (f=factor(n)); f[1,1]^a(f[1,2]))
Comments