# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a342480 Showing 1-1 of 1 %I A342480 #8 Mar 14 2021 05:14:38 %S A342480 1,6,10,15,1155,1365,12155,1616615,37182145,11849255,33426748355, %T A342480 247357937827,10141675450907,25652473199353,2928046583754721, %U A342480 155186468939000213,223317113839049087,558516101711461766587,796182527971658263007,241532826894674874877669,430046252763689411367557 %N A342480 a(n) is the denominator of the asymptotic density of numbers whose second smallest prime divisor (A119288) is prime(n). %C A342480 See A342479 for details. %H A342480 Amiram Eldar, Table of n, a(n) for n = 1..376 %t A342480 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] %Y A342480 Cf. A038110, A038111, A119288, A342479 (numerators). %K A342480 nonn,easy,frac %O A342480 1,2 %A A342480 _Amiram Eldar_, Mar 13 2021 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE