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Search: id:A108948
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| A108948 |
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Numbers n such that (n!/n#)^2 + 1 is prime, where n# = primorial numbers (A034386). |
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+0
1
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| 1, 2, 3, 4, 5, 6, 7, 12, 13, 22, 23, 39, 50, 54, 60, 61, 69, 182, 620, 767, 1308, 5129
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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n!/n# is known as n compositorial. All values have been proved prime. Primality proof for the largest, which has 29223 digits: PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing (5129!/5129#)^2+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 2591 Calling Brillhart-Lehmer-Selfridge with factored part 33.59% (5129!/5129#)^2+1 is prime! (164.5911s+0.0122s)
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CROSSREFS
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Sequence in context: A023762 A032903 A028819 this_sequence A107818 A039952 A129978
Adjacent sequences: A108945 A108946 A108947 this_sequence A108949 A108950 A108951
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KEYWORD
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more,nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Jul 21 2005
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