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 A090100 Numbers n such that n and the four successive integers produce primes if substituted for x in the polynomial 5x^2+5x+1. See A090562, A090563. Terms show that longer similar chains also exist. 2
 1, 2, 3, 13, 266, 321, 322, 323, 344, 641, 1324, 5436, 16700, 16701, 19857, 19858, 28151, 28152, 30648, 31253, 32045, 45773, 48710, 50923, 52397, 57357, 57358, 63879, 63880, 63881, 72615, 73164, 73165, 78785, 81831, 87640, 87641, 91116 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS MATHEMATICA Do[s=5*n^2+5*n+1; s1=5*(n+1)^2+5*(n+1)+1; s2=5*(n+2)^2+5*(n+2)+1; s3=5*(n+3)^2+5*(n+3)+1; s4=5*(n+4)^2+5*(n+4)+1; If[PrimeQ[s]&&PrimeQ[s1]&&PrimeQ[s2]&& PrimeQ[s3]&&PrimeQ[s4], Print[n]], {n, 1, 100000}] CROSSREFS Cf. A090562, A090563. Sequence in context: A270403 A119564 A132358 * A270314 A132484 A258357 Adjacent sequences:  A090097 A090098 A090099 * A090101 A090102 A090103 KEYWORD easy,nonn AUTHOR Labos Elemer, Dec 12 2003 STATUS approved

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Last modified May 10 22:35 EDT 2021. Contains 343780 sequences. (Running on oeis4.)