cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A242380 Lesser of consecutive primes whose average is a perfect power.

Original entry on oeis.org

3, 7, 61, 79, 139, 223, 317, 439, 619, 1087, 1669, 1723, 2593, 3593, 4093, 5179, 6079, 8461, 12541, 13687, 16633, 17573, 19037, 19597, 21943, 25261, 27211, 28219, 29581, 36857, 38011, 39199, 45361, 46649, 47521, 51977, 56167, 74527, 87013, 88801, 91807, 92413, 95479
Offset: 1

Views

Author

Antonio Roldán, May 12 2014

Keywords

Examples

			4093 is in the sequence because 4093 and 4099 are consecutive primes and (4093 + 4099)/2 = 4096 = 2^12.
		

Crossrefs

Supersequence of A225195 and A242382.
Cf. A091624.

Programs

  • Mathematica
    Select[Partition[Prime[Range[2, 10^4]], 2, 1], GCD @@ FactorInteger[(First[#] + Last[#])/2][[;; , 2]] > 1 &][[;; , 1]] (* Amiram Eldar, Jul 04 2022 *)
  • PARI
    for(i=3, 10^5, if(isprime(i), k=(i+nextprime(i+1))/2; if(ispower(k), print1(i, ", "))))