# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a096625 Showing 1-1 of 1 %I A096625 #15 Jan 09 2019 19:27:28 %S A096625 1,1,1,2,2,2,2,6,3,3,3,3,3,3,3,12,12,12,12,12,12,12,12,12,12,12,12,12, %T A096625 12,12,12,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60, %U A096625 60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60 %N A096625 Denominators of the Riemann prime counting function. %H A096625 Eric Weisstein's World of Mathematics, Riemann Prime Counting Function %e A096625 0, 1, 2, 5/2, 7/2, 7/2, 9/2, 29/6, 16/3, 16/3, 19/3, ... %t A096625 Table[Sum[PrimePi[x^(1/k)]/k, {k, Log2[x]}], {x, 100}] // Denominator (* _Eric W. Weisstein_, Jan 09 2019 *) %o A096625 (PARI) a(n) = denominator(sum(k=1, n, if (p=isprimepower(k), 1/p))); \\ _Michel Marcus_, Jan 07 2019 %o A096625 (PARI) a(n) = denominator(sum(k=1, logint(n, 2), primepi(sqrtnint(n, k))/k)); \\ _Daniel Suteu_, Jan 07 2019 %Y A096625 Cf. A096624. %K A096625 nonn,frac %O A096625 1,4 %A A096625 _Eric W. Weisstein_, Jul 01 2004 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE