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 A095874 If n = k-th prime power then k else 0. 19
 1, 2, 3, 4, 5, 0, 6, 7, 8, 0, 9, 0, 10, 0, 0, 11, 12, 0, 13, 0, 0, 0, 14, 0, 15, 0, 16, 0, 17, 0, 18, 19, 0, 0, 0, 0, 20, 0, 0, 0, 21, 0, 22, 0, 0, 0, 23, 0, 24, 0, 0, 0, 25, 0, 0, 0, 0, 0, 26, 0, 27, 0, 0, 28, 0, 0, 29, 0, 0, 0, 30, 0, 31, 0, 0, 0, 0, 0, 32, 0, 33, 0, 34, 0, 0, 0, 0, 0, 35, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = Sum(A010055(n): 1<=k<=n); a(n) = A065515(n)*(A065515(n)-A065515(n-1)). LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 MATHEMATICA Join[{1}, Module[{k=2}, Table[If[PrimePowerQ[n], k; k++, 0], {n, 2, 100}]]] (* Harvey P. Dale, Aug 15 2020 *) PROG (Haskell) a095874 n | y == n    = length xs + 1           | otherwise = 0           where (xs, y:ys) = span (< n) a000961_list -- Reinhard Zumkeller, Feb 16 2012, Jun 26 2011 (PARI) a(n)=if(isprimepower(n), sum(i=1, logint(n, 2), primepi(sqrtnint(n, i)))+1, n==1) \\ Charles R Greathouse IV, Apr 29 2015 CROSSREFS Cf. A000961, A049084. Sequence in context: A257846 A203572 A195829 * A279385 A267000 A224892 Adjacent sequences:  A095871 A095872 A095873 * A095875 A095876 A095877 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jun 10 2004 STATUS approved

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Last modified April 11 00:03 EDT 2021. Contains 342877 sequences. (Running on oeis4.)