0,2

Partial sums of number of Giuga sequences of length n. The only known primes in this partial sum are 3 and 23.

Table of n, a(n) for n=0..4.

a(n) = SUM[i=0..n] A029876(i) = SUM[i=0..n] {numbers i such that p divides i/p - 1 for every prime divisor p of i}.

a(4) = 1 + 2 + 3 + 17 + 27 = 50.

Cf. A007850, A029876.

Sequence in context: A117850 A090910 A256674 * A151443 A148643 A240646

Adjacent sequences: A176421 A176422 A176423 * A176425 A176426 A176427

nonn

Jonathan Vos Post, Apr 17 2010

approved