OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..407
FORMULA
a(n) = A283454(n)^2. - Amiram Eldar, Feb 12 2021
EXAMPLE
A249025(3)=5, 3^5-1 = 242 = 2*11*11. 242 is not squarefree the square being 11*11 = 121.
MATHEMATICA
psq[n_] := If[(f = Select[FactorInteger[n], Last[#] > 1 &]) == {}, 1, f[[1, 1]]^2]; psq /@ Select[3^Range[100] - 1, !SquareFreeQ[#] &] (* Amiram Eldar, Feb 12 2021 *)
PROG
(PARI) lista(nn) = {for (n=1, nn, if (!issquarefree(k = 3^n-1), f = factor(k/core(k)); vsq = select(x->((x%2) == 0), f[, 2], 1); print1(f[vsq[1], 1]^2, ", "); ); ); } \\ Michel Marcus, Mar 11 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Price, Mar 07 2017
EXTENSIONS
More terms from Michel Marcus, Mar 11 2017
STATUS
approved