OFFSET
3,1
LINKS
Eric Weisstein's World of Mathematics, Centered Polygonal Number
Eric Weisstein's World of Mathematics, Distinct Prime Factors
EXAMPLE
a(3) = 460, because 460 is a centered triangular number with 3 distinct prime factors {2, 5, 23} and this is the smallest such number.
PROG
(PARI) a(n) = if(n<3, return()); for(k=1, oo, my(t=((n*k*(k+1))/2+1)); if(omega(t) == n, return(t))); \\ Daniel Suteu, Dec 05 2022
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Ilya Gutkovskiy, Dec 05 2022
EXTENSIONS
a(8)-a(9) from Daniel Suteu, Dec 05 2022
a(10)-a(12) from Daniel Suteu, Dec 06 2022
STATUS
approved