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Search: id:A088631
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| A088631 |
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Largest number m < n such that m+n is a prime. |
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+0
5
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| 1, 2, 3, 2, 5, 6, 5, 8, 9, 8, 11, 10, 9, 14, 15, 14, 13, 18, 17, 20, 21, 20, 23, 22, 21, 26, 25, 24, 29, 30, 29, 28, 33, 32, 35, 36, 35, 34, 39, 38, 41, 40, 39, 44, 43, 42, 41, 48, 47, 50, 51, 50, 53, 54, 53, 56, 55, 54, 53, 52, 51, 50, 63, 62, 65, 64, 63, 68, 69, 68, 67, 66, 65, 74, 75
(list; graph; listen)
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OFFSET
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2,2
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REFERENCES
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F. W. Roush and D. G. Rogers, A prime algorithm?, preprint, 1999.
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FORMULA
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a(n) = p-n where p = largest prime <= 2n-1.
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EXAMPLE
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Adding 1,2,3,2,5 to 2,3,4,5,6 we get the primes 3,5,7,7,11.
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MAPLE
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with(numtheory); A088631 := n->prevprime(2*n)-n;
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CROSSREFS
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Cf. A088633. Second column of A088643.
Sequence in context: A070673 A070669 A088861 this_sequence A086184 A056552 A049273
Adjacent sequences: A088628 A088629 A088630 this_sequence A088632 A088633 A088634
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KEYWORD
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easy,nonn
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AUTHOR
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njas, Nov 24 2003
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