A342480 a(n) is the denominator of the asymptotic density of numbers whose second smallest prime divisor (A119288) is prime(n).

1, 6, 10, 15, 1155, 1365, 12155, 1616615, 37182145, 11849255, 33426748355, 247357937827, 10141675450907, 25652473199353, 2928046583754721, 155186468939000213, 223317113839049087, 558516101711461766587, 796182527971658263007, 241532826894674874877669, 430046252763689411367557

Offset: 1

Author

Amiram Eldar, Mar 13 2021

Keywords

• nonn
• easy
• frac

Comments

See A342479 for details.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..376

Crossrefs

Cf. A038110, A038111, A119288, A342479 (numerators).

Programs

Mathematica

f[n_] := Module[{p = Prime[n], q}, q = Select[Range[p - 1], PrimeQ]; Plus @@ (1/(q - 1))*Times @@ ((q - 1)/q)/p]; Denominator @ Array[f, 30]