OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..450
EXAMPLE
a(3) = 36 is a term because A001414(36) = 2*2+2*3 = 10 and 36*10+1 = 361 = 19^2 where 19 is prime.
MAPLE
sopf:= proc(x) local t; add(t[1]*t[2], t=ifactors(x)[2]) end proc:
filter:= proc(n) local x;
x:= n*sopf(n)+1;
issqr(x) and isprime(sqrt(x))
end proc:
select(filter, [$1..10^5]);
MATHEMATICA
Select[Range[150000], PrimeQ@ Sqrt[#*Total@ Flatten[ConstantArray @@@ FactorInteger[#]] + 1] &] (* Michael De Vlieger, Apr 06 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Apr 06 2021
STATUS
approved