OFFSET
0,1
EXAMPLE
a(6)=30600 because the divisors of 13#+1 = 30031 are {1, 59, 509, 30031}.
MAPLE
seq(numtheory[sigma](mul(ithprime(k), k=1..n)-1), n=0..30);
MATHEMATICA
Map[DivisorSigma[1, #] &, 1 + FoldList[Times, 1, Prime@ Range@ 19] ] (* Michael De Vlieger, Oct 25 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 23 2023
STATUS
approved