A114434 To obtain a(n), write the n-th composite number as a product of primes, add 1 to each prime and multiply.
9, 12, 27, 16, 18, 36, 24, 24, 81, 48, 54, 32, 36, 108, 36, 42, 64, 72, 72, 243, 48, 54, 48, 144, 60, 56, 162, 96, 108, 96, 72, 324, 64, 108, 72, 126, 192, 72, 216, 80, 90, 216, 96, 128, 729, 84, 144, 162, 96, 144, 432, 114, 144, 180, 96, 168, 486, 256
Offset: 1
Keywords
Links
- Alois P. Heinz, Table of n, a(n) for n = 1..10000
Programs
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Maple
b:= proc(n) option remember; local k; for k from 1+`if`(n=1, 3, b(n-1)) while isprime(k) do od; k end: a:= n-> mul((i[1]+1)^i[2], i=ifactors(b(n))[2]): seq(a(n), n=1..100); # Alois P. Heinz, Oct 23 2014 -
Mathematica
f[n_] := Module[{p, e}, Product[{p, e} = pe; (p+1)^e, {pe, FactorInteger[n]}]]; f /@ Select[Range[1000], CompositeQ] (* Jean-François Alcover, Jul 11 2021 *) -
PARI
lista(nn) = {forcomposite(c=2, nn, f = factor(c); print1(prod(i=1, #f~, (f[i,1]+1)^f[i,2]), ", "););} \\ Michel Marcus, Jun 26 2013
Formula
Extensions
More terms from Michel Marcus, Jun 26 2013