OFFSET
1,2
COMMENTS
Pentagonal number analogy of A112886 (the triangle-free positive integers).
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
EXAMPLE
10 is not a term, since 10 = 2 * 5 and 5 is the first nontrivial pentagonal number.
24 is not a term, since 12|24 and 12 is a pentagonal number.
44 is not a term, since 22|44 and 22 is a pentagonal number.
MATHEMATICA
Select[Range[1, 101], {} == Intersection[{5, 12, 22, 35, 51, 70, 92}, Divisors[#]] &] (* Giovanni Resta, Jun 13 2016 *)
PROG
(PARI) is(n)=fordiv(n, d, if(ispolygonal(d, 5) && d>1, return(0))); 1 \\ Charles R Greathouse IV, Dec 24 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jan 11 2006
EXTENSIONS
Data corrected by Giovanni Resta, Jun 13 2016
a(1)=1 inserted by Andrew Howroyd, Sep 08 2024
STATUS
approved