A264744
Exponent of the prime power A264734(n).
Original entry on oeis.org
1, 1, 1, 2, 1, 2, 3, 1, 4, 1, 1, 1, 1
Offset: 1
a(9) = 4 is the exponent of 81 = A264734(9) = 3^4.
Cf.
A025474,
A264734 (prime power k such that both k - 2 and k + 2 is a prime power).
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t = Prepend[Select[Range@ 100000, AllTrue[{# - 2, #, # + 2}, PrimePowerQ] &], 3]; Flatten@ Map[Last, FactorInteger@ # &@ t, {2}] (* Michael De Vlieger, Dec 03 2015, Version 10 *)
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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
A269721
Integers k such that k, k+2, k+4 and k+6 are prime powers (A000961).
Original entry on oeis.org
1, 3, 5, 7, 23, 25
Offset: 1
5 is a term because 5, 7, 11 are prime numbers and 9 = 3^2.
23 is a term because 23 and 29 are prime numbers and 25 = 5^2, 27 = 3^3.
25 is a term because 25 = 5^2, 27 = 3^3, 29 and 31 are prime numbers.
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Select[Range[0, 10^5], AllTrue[Range[0, 6, 2] + #, Or[# == 1, PrimePowerQ@ #] &] &] (* Michael De Vlieger, Mar 04 2016, Version 10 *)
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lista(nn) = for(n=1, nn, if(n==1 || (isprimepower(n) && isprimepower(n+2) && isprimepower(n+4) && isprimepower(n+6)), print1(n, ", ")));
Showing 1-2 of 2 results.
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