cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A381113 Decimal expansion of the asymptotic mean of the second smallest prime not dividing k, where k runs over the positive integers (A380539).

Original entry on oeis.org

5, 1, 5, 9, 1, 4, 2, 8, 5, 9, 6, 5, 1, 6, 4, 2, 0, 3, 0, 1, 3, 6, 5, 8, 0, 9, 7, 4, 5, 0, 1, 2, 5, 8, 1, 7, 2, 0, 0, 0, 7, 3, 0, 7, 2, 1, 4, 1, 9, 1, 6, 7, 9, 9, 3, 5, 0, 0, 6, 6, 3, 8, 8, 6, 6, 2, 4, 5, 4, 2, 4, 3, 7, 8, 8, 1, 0, 7, 1, 2, 1, 2, 1, 9, 9, 5, 3, 5, 3, 3, 9, 3, 6, 1, 5, 1, 0, 5, 0, 0, 1, 1, 9, 4, 9
Offset: 1

Views

Author

Amiram Eldar, Feb 14 2025

Keywords

Examples

			5.15914285965164203013658097450125817200073072141916...
		

Crossrefs

Cf. A002110, A007504, A249270 (analogous constant with smallest prime), A380539.

Programs

  • PARI
    primorial(k) = prod(i = 1, k, prime(i));
    primesum(k) = sum(i = 1, k, prime(i));
    suminf(k = 2, prime(k) * (prime(k)-1) * (primesum(k-1)-k+1) / primorial(k))

Formula

Equals lim_{m->oo} (1/m) * Sum_{k=1..m} A380539(k).
Equals Sum_{k>=2} prime(k) * (prime(k)-1) * (primesum(k-1)-k+1) / primorial(k), where primesum(k) = A007504(k) and primorial(k) = A002110(k).