A178700 Lonely primes between two consecutive nontrivial powers.
127, 223, 251, 64007, 1295033, 2535525373, 542939080319
Offset: 1
Examples
5^3 < 127 < 2^7; 6^3 < 223 < 15^2; 3^5 < 251 < 2^8; 40^3 < 64007 < 253^2; 109^3 < 1295033 < 1138^2. From _Carlos Rivera_, Nov 26 2013: (Start) 50354^2 < 2535525373 < 76^5; 8158^3 < 542939080319 < 736844^2. (End)
Programs
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Mathematica
nextPerfectPower[n_] := Block[{k = n + 1}, While[ GCD @@ Last /@ FactorInteger@k == 1, k++ ]; k]; a = 1; b = 3; lst = {}; While[a < 15 10^8, If[ PrimePi@b == 1 + PrimePi@a, p = NextPrime@a; AppendTo[lst, p]; Print@p]; a = b; b = nextPerfectPower@b]; lst (* Robert G. Wilson v, Jun 10 2010 *)
Extensions
First 5 terms checked by Robert G. Wilson v, Jun 10 2010
a(6)-a(7) from Carlos Rivera, Nov 26 2013
Comments