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%I #5 Oct 15 2013 22:32:21
%S 11,516811,20402952601,196260616589761,239536538008051,
%T 426813020692661,2681027962124411,3605832801512401,6450361508166761,
%U 10392841156929031,13162202092936411,13655671002023851,14501847401205811
%N Leading prime in each set of 7 arising in A090101.
%e 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.
%t 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}]
%Y Cf. A090562, A090563, A090100, A090101, A056561.
%K nonn
%O 1,1
%A _Labos Elemer_, Dec 15 2003
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