OFFSET
1,1
COMMENTS
Numbers k such that the k-th triangular number mod the sum (with multiplicity) of prime factors of k is prime.
Contains p^2 for prime p.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
MAPLE
filter:= proc(n) local t; isprime((n*(n+1)/2) mod add(t[1]*t[2], t=ifactors(n)[2])) end proc:
select(filter, [$2..500]);
MATHEMATICA
Select[Range[300], PrimeQ[Mod[#*(# + 1)/2, Plus @@ Times @@@ FactorInteger[#]]] &] (* Amiram Eldar, Apr 14 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Apr 14 2022
STATUS
approved