A167188 Smaller prime power associated with record gap in A167186.

1, 4, 9, 16, 32, 81, 128, 169, 361, 1024, 1369, 2401, 4489, 5329, 6889, 8192, 12769, 19683, 32768, 39601, 44521, 85849, 177241, 218089, 262144, 279841, 436921, 597529, 744769, 786769, 1142761, 1771561, 5340721, 6135529, 8826841, 10699441, 17447329, 18464209

Offset: 1

Author

Michael B. Porter, Nov 01 2009

Keywords

• nonn

Examples

			32 is in the sequence since the gap between 32 and the next prime power, 49, is greater than any previous gap.
		

Links

• Donovan Johnson, Table of n, a(n) for n = 1..200

Crossrefs

Larger prime power: A167189.

Record gaps between nonprime prime powers: A167186.

Gaps between nonprime prime powers: A053707.

List of nonprime prime powers: A025475.

Programs

PARI

isA025475(n) = (omega(n) == 1 & !isprime(n)) || (n == 1)
d_max=0;n_prev=1;for(n=2,32e6,if(isA025475(n),d=n-n_prev;if(d>d_max,print(n_prev);d_max=d);n_prev=n))