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A120224
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a(n) is the minimal number k>=n such that n+k and n*k+1 are primes.
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5
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1, 3, 4, 7, 6, 7, 10, 9, 14, 13, 18, 19, 24, 15, 16, 21, 24, 29, 22, 21, 22, 31, 30, 43, 28, 33, 34, 39, 32, 41, 36, 39, 34, 37, 66, 43, 60, 41, 50, 43, 42, 55, 46, 53, 52, 51, 50, 59, 52, 51, 56, 55, 56, 55, 58, 75, 74, 69, 68, 67, 66, 75, 74, 67, 86, 83, 70, 89, 70, 79, 102, 79
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Differs from A120225 in the first term.
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EXAMPLE
| a(3)=4 because 3+4=7 and 3*4+1=13 are prime;
a(8)=9 because 8+9=17 and 8*9+1=73 are prime,
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MATHEMATICA
| Reap[Do[Do[If[PrimeQ[{n+x, n*x+1}]=={True, True}, Sow[x]; Break[]], {x, n, 1000}], {n, 120}]][[2, 1]]
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CROSSREFS
| Cf. A085063, A092945, A085063, A120223, A120225.
Sequence in context: A023888 A117553 A168275 * A183107 A132009 A086455
Adjacent sequences: A120221 A120222 A120223 * A120225 A120226 A120227
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KEYWORD
| nonn
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Jun 10 2006
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