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A104635
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Odd n such that 2n+1 is prime.
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3
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1, 3, 5, 9, 11, 15, 21, 23, 29, 33, 35, 39, 41, 51, 53, 63, 65, 69, 75, 81, 83, 89, 95, 99, 105, 111, 113, 119, 125, 131, 135, 141, 153, 155, 165, 173, 179, 183, 189, 191, 209, 215, 219, 221, 231, 233, 239, 243, 245, 249, 251, 261
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Also: Numbers k such that 2k+1 is in A002145, i.e., a Gaussian prime. - M. F. Hasler, Feb 25 2011
Also: Number of quadratic residues modulo A002145(n). - M. F. Hasler, Feb 25 2011
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FORMULA
| a(n) = floor(A002145(n)/2). - M. F. Hasler, Feb 25 2011
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PROG
| (PARI) forstep( k=1, 250, 2, isprime(2*k+1) & print1(k", ")) \\ - M. F. Hasler, Feb 25 2011
(PARI) forprime( p=1, 500, p%4==3 | next; print1(p\2", ")) \\ - M. F. Hasler, Feb 25 2011
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CROSSREFS
| Cf. A005097, A104636.
Sequence in context: A006046 A161830 A151922 * A199407 A169780 A024903
Adjacent sequences: A104632 A104633 A104634 * A104636 A104637 A104638
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KEYWORD
| easy,nonn
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Mar 18 2005
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