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A174030 Partial sums of A007694. 0
1, 3, 7, 13, 21, 33, 49, 67, 91, 123, 159, 207, 261, 325, 397, 493, 601, 729, 873, 1035, 1227, 1443, 1699, 1987, 2311, 2695, 3127, 3613, 4125, 4701, 5349, 6117, 6981, 7953, 8977, 10129, 11425, 12883, 14419, 16147, 18091, 20139, 22443, 25035, 27951, 31023 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..46.

FORMULA

a(n) = SUM[i=1..n] A007694(i) = SUM[i=1..n] {Numbers i such that phi(i) divides i}.

EXAMPLE

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.

CROSSREFS

Cf. A000010, A007694.

Sequence in context: A147342 A172310 A060939 * A098575 A138035 A032606

Adjacent sequences:  A174027 A174028 A174029 * A174031 A174032 A174033

KEYWORD

nonn

AUTHOR

Jonathan Vos Post, Mar 06 2010

STATUS

approved

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Last modified October 16 06:02 EDT 2019. Contains 328046 sequences. (Running on oeis4.)