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A090102
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Leading prime in each set of 7 arising in A090101.
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8
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11, 516811, 20402952601, 196260616589761, 239536538008051, 426813020692661, 2681027962124411, 3605832801512401, 6450361508166761, 10392841156929031, 13162202092936411, 13655671002023851, 14501847401205811
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a[15] = 69981018761651281 is first of following chain: {69981018761651281, 69981019944706811, 69981021127762351, 69981022310817901, 69981023493873461, 69981024676929031, 69981025859984611} = {P[k], P[k+1], ..., P[k+6]}, where k = A090101[15] and P[x] = 5x^2+5x+1. See A090562, A090563.
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MATHEMATICA
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po[x_] := 5*x^2+5*x+1 Do[s=po[n]; s0=po[n]; s1=po[n+1]; s2=po[n+2]; s3=po[n+3]; s4=po[n+4]; s5=po[n+5]; s6=po[n+6]; If[IntegerQ[n/100000], Print[{n}]]; If[PrimeQ[s0]&&PrimeQ[s1]&&PrimeQ[s2]&&PrimeQ[s3]&&PrimeQ[s4]&&PrimeQ[s5] &&PrimeQ[s6], Print[s0]], {n, 1, 120000000}]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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