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Search: id:A028372
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| A028372 |
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Smallest prime that is simultaneously of forms x^2 + m y^2 for m = 1, ..., n. |
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+0
5
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| 2, 2, 73, 73, 241, 241, 1009, 1009, 1009, 1009, 7561, 7561, 21961, 35281, 35281, 35281, 44641, 44641, 374089, 622561, 622561, 622561, 4379281, 4379281, 4379281, 17690689, 17690689, 17690689, 17690689, 17690689, 316234801
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Sequence A155715 lists the smallest numbers of this kind with x,y>0, but not necessarily prime. [From M. F. Hasler (MHasler(AT)univ-ag.fr), Jan 27 2009]
a(n) > 10^9 for n >= 32. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 29 2009]
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PROGRAM
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(PARI) p=2; for(k=1, 999, forstep( c=k, 1, -1, for( b=1, sqrtint(p\c), issquare(p-c*b^2) & next(2)); p=nextprime(p+1); c=k+1); print1(p", ")) [From M. F. Hasler (MHasler(AT)univ-ag.fr), Jan 27 2009]
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CROSSREFS
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Sequence in context: A015167 A086204 A037292 this_sequence A130678 A156523 A156511
Adjacent sequences: A028369 A028370 A028371 this_sequence A028373 A028374 A028375
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KEYWORD
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nonn
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AUTHOR
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John L. Drost (drost(AT)marshall.edu)
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EXTENSIONS
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a(17)-a(18) corrected and a(26)-a(31) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 29 2009
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