A163631 - OEIS

%I #17 Aug 01 2017 02:53:35

%S 1,10,25,46,71,98,131,166,205,250,299,350,405,462,525,590,659,734,811,

%T 892,977,1064,1155,1248,1343,1442,1547,1658,1773,1890,2009,2130,2253,

%U 2378,2507,2640,2775,2916,3059,3204,3351,3504,3659,3818,3979,4144,4313

%N Partial sums of the odd nonprimes, A014076.

%C All entries besides the first are of the form 2+(k+1)^2-A007504(j), e.g., 10=2+25-17, 25=2+64-41, where the square is the sum of all odd numbers up to 1+2*k, and the 2 and A007504 represent the partial sum over the primes.

%H G. C. Greubel, <a href="/A163631/b163631.txt">Table of n, a(n) for n = 1..5000</a>

%F a(n) = Sum_{x= 1st odd nonprime..n-th odd nonprime}x.

%t upto=200; Accumulate[Complement[Range[1,upto,2], Prime[Range[2,PrimePi[upto]]]]] (* _Harvey P. Dale_, Mar 19 2011 *)

%o (PARI) lista(nn) = {my(s = 0); forstep (n=1, nn, 2, if (!isprime(n), s+= n; print1(s, ", ")););} \\ _Michel Marcus_, Aug 01 2017

%Y Cf. A014076.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Aug 02 2009, Oct 10 2009

%E 150 replaced with 250 by _R. J. Mathar_, Aug 06 2009