OFFSET
1,1
COMMENTS
De Koninck et al. calculated the first 50 terms of this sequence.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..50
Jean-Marie De Koninck, Nicolas Doyon, Florian Luca, and Michoacán Morelia, Powerful values of quadratic polynomials, Journal of Integer Sequences, Vol. 14, No. 3 (2011), Article 11.3.3.
FORMULA
a(2) = 11427 since 11427^2 - 2 = 130576327 = 7^3 * 617^2 is a nonsquare powerful number, and k^2 - 2 is not a nonsquare powerful number for all k < 11427.
PROG
(PARI) is_a102834(n) = ispowerful(n) && !issquare(n) \\ after Charles R Greathouse IV in A102834
a(n) = for(k=1, oo, if(n%k!=0 && is_a102834(k^2-n), return(k))) \\ Felix Fröhlich, Jul 19 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jul 18 2019
STATUS
approved