A264744 Exponent of the prime power A264734(n).

1, 1, 1, 2, 1, 2, 3, 1, 4, 1, 1, 1, 1

Offset

1,4

Comments

Subsequence of A025474.

Links

Table of n, a(n) for n=1..13.

Example

a(9) = 4 is the exponent of 81 = A264734(9) = 3^4.

Mathematica

t = Prepend[Select[Range@ 100000, AllTrue[{# - 2, #, # + 2}, PrimePowerQ] &], 3]; Flatten@ Map[Last, FactorInteger@ # &@ t, {2}] (* Michael De Vlieger, Dec 03 2015, Version 10 *)

Prog

(PARI) is(k) = isprimepower(k) || k==1;
for(k=1, 1e6, if(is(k) && is(k+2) && is(k-2), print1(bigomega(k), ", "))) \\ Altug Alkan, Nov 23 2015

Crossrefs

Cf. A025474, A264734 (prime power k such that both k - 2 and k + 2 is a prime power).

Sequence in context: A283827 A122087 A139642 * A354322 A358532 A143604

Adjacent sequences: A264741 A264742 A264743 * A264745 A264746 A264747

Keyword

nonn,more,less

Author

Juri-Stepan Gerasimov, Nov 22 2015

Status

approved