A097019 a(n) = sigma(A097018(n))/prime(n) = A000203(A097018(n))/A000040(n).
2, 1, 3, 1, 4, 1, 4, 2, 6, 6, 1, 2, 4, 6, 6, 4, 6, 3, 6, 4, 7, 2, 4, 23, 2, 10, 6, 6, 6, 6, 1, 4, 4, 2, 10, 12, 2, 6, 10, 4, 10, 8, 22, 8, 4, 2, 2, 8, 4, 2, 16, 6, 14, 12, 12, 4, 6, 2, 12, 4, 6, 4, 1, 10, 6, 6, 2, 2, 6, 8, 10, 6, 2, 6, 2, 4, 6, 6, 22, 7, 16, 12, 4, 8, 2, 6, 6, 6, 12, 6, 4, 10, 12, 10, 2
Offset: 1
Keywords
Examples
For n = 11: the quotient of the least number whose sigma is divisible by the 11th prime is A097018(11) = 16, sigma(16) = 31, and prime(11) = 31, so, a(11) = 31/31 = 1.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
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PARI
list(len) = {my(v = vector(len), p = primes(len), k = 1, c = 0, s); while(c < len, s = sigma(k); for(i = 1, len, if(v[i] == 0 && !(s % p[i]), c++; v[i] = s/p[i])); k++); v;} \\ Amiram Eldar, Feb 15 2025