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%I #2 Mar 30 2012 18:40:51
%S 1,3,7,13,21,33,49,67,91,123,159,207,261,325,397,493,601,729,873,1035,
%T 1227,1443,1699,1987,2311,2695,3127,3613,4125,4701,5349,6117,6981,
%U 7953,8977,10129,11425,12883,14419,16147,18091,20139,22443,25035,27951,31023
%N Partial sums of A007694.
%C Partial sums of numbers n such that phi(n) divides n. The subsequence of primes in this partial sum begins: 3, 7, 13, 67, 397, 601, 1699, 1987, 2311, 3613, 14419, 42463.
%F a(n) = SUM[i=1..n] A007694(i) = SUM[i=1..n] {Numbers i such that phi(i) divides i}.
%e a(49) = 1 + 2 + 4 + 6 + 8 + 12 + 16 + 18 + 24 + 32 + 36 + 48 + 54 + 64 + 72 + 96 + 108 + 128 + 144 + 162 + 192 + 216 + 256 + 288 + 324 + 384 + 432 + 486 + 512 + 576 + 648 + 768 + 864 + 972 + 1024 + 1152 + 1296 + 1458 + 1536 + 1728 + 1944 + 2048 + 2304 + 2592 + 2916 + 3072 + 3456 + 3888 + 4096 = 42463 is prime.
%Y Cf. A000010, A007694.
%K nonn
%O 1,2
%A _Jonathan Vos Post_, Mar 06 2010
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