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A087338
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a(1) = 1, then smallest number >1 such that every partial sum as well as every partial product + 1 both are prime for n > 1.
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0
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1, 2, 2, 18, 6, 8, 30, 4, 26, 6, 6, 4, 50, 4, 56, 6, 22, 6, 50, 40, 12, 24, 138, 20, 132, 70, 78, 8, 232, 2, 160, 144, 32, 322, 12, 44, 216, 294, 60, 394, 1460, 82, 54, 452, 168, 1024, 86, 76, 308, 208, 104, 456, 268, 396, 350, 120, 10, 236, 180, 402, 112, 336, 530, 318, 112
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| Partial sums : 1+2 = 3, 1+2+2 = 5, 1+2+2+18 = 23; partial products + 1,1*2 + 1= 3, 1*2*2 +1 =5,1*2*2*18 + 1 = 73.
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MATHEMATICA
| a = {1}; s = 1; p = 1; Do[k = 2; While[ !PrimeQ[s + k] || !PrimeQ[p*k + 1], k++ ]; AppendTo[a, k]; s += k; p *= k, {n, 1, 65}]
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CROSSREFS
| Sequence in context: A206095 A000528 A074970 * A055735 A168296 A205454
Adjacent sequences: A087335 A087336 A087337 * A087339 A087340 A087341
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 06 2003
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 07 2003
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