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A090125 a(n) is the least positive integer such that nextprime[a(n)^n]-prevprime[a(n)^n]=4;. 5
5, 2, 2, 2, 411, 195, 2, 392, 141, 105, 1161, 909, 69, 3243, 171, 370, 1659, 165, 26289, 1065, 8541, 19593, 43521, 1323, 84651, 25767, 25641, 7029, 63009, 693, 231, 957, 2601, 7137, 368265, 14769, 8169, 13071, 23679, 45, 13875, 6693, 136611, 34869 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..44.

EXAMPLE

with q-p=4,q,p are primes:

n=1:a(1)=5 because {p=3,a(1)^1=5,q=5};

n=7:a(7)=2 because {p=127,a(7)^7=128, q=131};

n=10:a(10)=105 because {p=c-2,c=a(10)^10=162889462677744140625,q=c+2}

MATHEMATICA

Table[fla=1; Do[If[((PrimeQ[s=n^k-3]&&PrimeQ[s1=n^k+1]) ||(PrimeQ[s=n^k-2]&&PrimeQ[s1=n^k+2])||(PrimeQ[s=n^k-1] &&PrimeQ[s1=n^k+3]))&&Equal[fla, 1]&&!Equal[n, 1], Print[{n, p, n^k, q, {k}}]; fla=0], {n, 1, 1000000}], {k, 1, 60}]

CROSSREFS

Cf. A090121-A090125.

Sequence in context: A286016 A119320 A070962 * A093008 A297827 A198496

Adjacent sequences:  A090122 A090123 A090124 * A090126 A090127 A090128

KEYWORD

nonn

AUTHOR

Labos Elemer, Jan 12 2004

STATUS

approved

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Last modified March 22 01:06 EDT 2019. Contains 321406 sequences. (Running on oeis4.)