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%I M2523 N0996 #63 Feb 17 2024 08:17:32
%S 0,1,3,6,9,13,17,22,27,32,37,43,49,56,63,70,77,85,93,102,111,120,129,
%T 139,149,159,169,179,189,200,211,223,235,247,259,271,283,296,309,322,
%U 335,349,363,378,393,408,423,439,455,471
%N a(n) = n + Sum_{k=1..n} pi(k), where pi() = A000720.
%D H. Brocard, Reply to Query 1421, Nombres premiers dans une suite de différences, L'Intermédiaire des Mathématiciens, 7 (1900), 135-137.
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H T. D. Noe, <a href="/A002815/b002815.txt">Table of n, a(n) for n = 0..1000</a>
%F a(n) = A046992(n) + n for n > 0. - _Reinhard Zumkeller_, Feb 25 2012
%F Conjectured g.f.: (Sum_{N>=1} x^A008578(N))/(1-x)^2 = (x + x^2 + x^3 + x^5 + x^7 + x^11 + x^13 + ...)/(1-x)^2. - _L. Edson Jeffery_, Nov 25 2013
%t Table[n + Sum[PrimePi[k], {k, 1, n}], {n, 0, 50}]
%t Module[{nn=50,pp},pp=Accumulate[PrimePi[Range[0,nn]]];Total/@ Thread[ {Range[ 0,nn],pp}]] (* This program is significantly faster than the program above. *) (* _Harvey P. Dale_, Jan 03 2013 *)
%o (Haskell)
%o a002815 0 = 0
%o a002815 n = a046992 n + toInteger n -- _Reinhard Zumkeller_, Feb 25 2012
%o (Python)
%o from sympy import primerange
%o def A002815(n): return n+(n+1)*len(p:=list(primerange(n+1)))-sum(p) # _Chai Wah Wu_, Jan 01 2024
%o (PARI) a(n) = my(p=primes([0,n])); n + (n+1)*#p - vecsum(p); \\ _Ruud H.G. van Tol_, Feb 16 2024
%Y Cf. A000720, A046992.
%K nonn,nice,easy
%O 0,3
%A _N. J. A. Sloane_, _Robert G. Wilson v_, _Mira Bernstein_
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