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Search: id:A087200
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| A087200 |
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a(n) is the smallest m such that m > A05235(n) and A002110(n)+m is prime. |
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+0
3
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| 5, 7, 11, 17, 29, 29, 41, 37, 47, 89, 83, 101, 107, 67, 109, 73, 89, 167, 139, 229, 163, 193, 269, 157, 173, 523, 233, 157, 251, 193, 179, 383, 647, 311, 223, 317, 509, 457, 211, 503, 251, 479, 617, 1019, 347, 863, 827, 349, 389, 563, 601, 419, 367, 349, 449
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) is the second m (first m is A05235(n)) such that m > 1 and A002110(n)+m is prime. I guess every term of this sequence (compare the conjecture about A005235) is prime. I checked this conjecture for n < 373.
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REFERENCES
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R. K. Guy, Unsolved Problems in Number Theory, Section A2.
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FORMULA
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A005235[n_] := (For[m=2, !PrimeQ[Product[Prime[k], {k, n}]+m], m++ ]; m); a[n_] := (For[m=A005235[n]+1, !PrimeQ[Product[Prime[k], {k, n}]+m], m++ ]; m)
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MATHEMATICA
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A05235[n_] := (For[m=2, !PrimeQ[Product[Prime[k], {k, n}]+m], m++ ]; m); a[n_] := (For[m=A05235[n]+1, !PrimeQ[Product[Prime[k], {k, n}]+m], m++ ]; m); Table[a[n], {n, 60}]
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CROSSREFS
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Cf. A005235, A002110.
Sequence in context: A067830 A106862 A027690 this_sequence A145987 A060449 A046140
Adjacent sequences: A087197 A087198 A087199 this_sequence A087201 A087202 A087203
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KEYWORD
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easy,nonn
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Aug 26 2003
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