OFFSET
1,1
COMMENTS
Contains no prime powers or semiprimes.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(3) = 364 is a term because A341117(364) = 609149 is prime.
MAPLE
f:= proc(n) local D, S, i;
D:= sort(convert(numtheory:-divisors(n), list), `>`);
S:= ListTools:-PartialSums(D);
add(D[i]*S[-i], i=1..nops(D))
end proc:
select(t -> isprime(f(t)), [$1..4000]);
MATHEMATICA
Position[Array[Sum[#1[[k]]*Sum[#1[[j]], {j, #2 - k + 1, #2}], {k, #2}] & @@ {Divisors[#], DivisorSigma[0, #]} &, 3400], _?PrimeQ][[All, 1]] (* Michael De Vlieger, Feb 05 2021 *)
PROG
(PARI) f(n) = my(d=divisors(n)); sum(k=1, #d, d[k]*sum(i=#d-k+1, #d, d[i])); \\ A341117
isok(m) = isprime(f(m)); \\ Michel Marcus, Feb 05 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Feb 05 2021
STATUS
approved