A385628 Sum of the divisors d of n with an even number of primes not exceeding d.
1, 1, 4, 5, 1, 4, 8, 13, 13, 11, 1, 8, 14, 22, 19, 29, 1, 13, 20, 35, 32, 23, 1, 16, 1, 14, 13, 26, 30, 59, 1, 29, 4, 1, 8, 17, 38, 58, 56, 83, 1, 46, 44, 71, 73, 47, 1, 32, 8, 11, 4, 18, 54, 67, 56, 90, 80, 88, 1, 83, 62, 63, 104, 93, 79, 92, 1, 5, 4, 32, 72, 97, 1, 38, 19, 62, 8, 56, 80, 179, 94, 83, 1, 50, 1, 44, 33, 79, 90, 203, 112, 143, 97, 95, 115
Offset: 1
Examples
The sum of the divisors d of 16 such that pi(d) is even gives 1 + 4 + 8 + 16 = 29.
Programs
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Mathematica
Table[Sum[d*Mod[PrimePi[d] + 1, 2], {d, Divisors[n]}], {n, 100}]
Comments