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Search: id:A115606
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| A115606 |
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Partial sums of A102540 (primes that are not Chen primes). |
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+0
1
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| 0, 43, 104, 177, 256, 353, 456, 607, 770, 943, 1136, 1359, 1588, 1829, 2100, 2377, 2660, 2973, 3304, 3653, 4020, 4393, 4776, 5173, 5594, 6027, 6466, 6923, 7386, 7909, 8456, 9049, 9650, 10257, 10870, 11489, 12132, 12793, 13466, 14157, 14866, 15593
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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See also A109611 (Chen primes: primes p such that p + 2 is either a prime or a semiprime), A102540 (primes that are not Chen primes). a(n) is prime for a(1) = 43, a(5) = 353 [Chen prime], a(7) = 607, a(15) = 2377, a(31) = 9049, a(35) = 11489 [Chen prime], a(49) = 22013. a(n) is semiprime for a(3) = 177, a(9) = 943, a(13) = 1829, a(17) = 2973, a(19) = 3653, a(21) = 4393, a(23) = 5173, a(24) = 5594, a(29) = 7909, a(37) = 12793, a(38) = 13466, a(40) = 14866, a(41) = 15593, a(43) = 17065, a(45) = 18595.
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FORMULA
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a(n) = SUM[k=1..n] A102540(k).
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EXAMPLE
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a(5) = 43 + 61 + 73 + 79 + 97 = 353, which happens to be the Chen prime A109611(52).
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CROSSREFS
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Cf. A000040, A001358, A007504, A102540, A109611.
Sequence in context: A106888 A142795 A023293 this_sequence A154506 A044230 A044611
Adjacent sequences: A115603 A115604 A115605 this_sequence A115607 A115608 A115609
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Mar 09 2006
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