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S[A002808(n)] where S[] is Boris Stechkin's function (A055004) and A002808(n) are the composites.
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%I #11 Dec 15 2017 17:35:22

%S 0,0,15,64,171,252,359,656,1079,1346,1656,2415,3373,3927,4550,5993,

%T 6793,7690,8653,9697,12028,14695,16158,17731,19398,21174,25017,27108,

%U 29318,34077,39324,42128,45071,51398,54716,58239,61877,65685,73758

%N S[A002808(n)] where S[] is Boris Stechkin's function (A055004) and A002808(n) are the composites.

%H Harry J. Smith, <a href="/A063483/b063483.txt">Table of n, a(n) for n=0,...,1000</a>

%o (PARI) S(n)=sum(k=2,n,(k-1)*floor(n*(k-1)/k)); j=[]; for(n=0,80, if(isprime(n), n+1,j=concat(j,S(n)))); j

%o (PARI) { n=-1; for (m=0, 10^9, if (!isprime(m), a=sum(k=2, m, (k - 1)*floor(m*(k - 1)/k)); write("b063483.txt", n++, " ", a); if (n==1000, break)) ) } \\ _Harry J. Smith_, Aug 23 2009

%Y Cf. A002808, A055004.

%K nonn

%O 0,3

%A _Jason Earls_, Jul 28 2001