

A167188


Smaller prime power associated with record gap in A167186.


2



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
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OFFSET

1,2


LINKS

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


EXAMPLE

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


PROG

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


CROSSREFS

Larger prime power: A167189
Record gaps between nonprime prime powers: A167186
Gaps between nonprime prime powers: A053707
List of nonprime prime powers: A025475
Sequence in context: A007679 A239870 A068037 * A014764 A068952 A100498
Adjacent sequences: A167185 A167186 A167187 * A167189 A167190 A167191


KEYWORD

nonn


AUTHOR

Michael B. Porter, Nov 01 2009


STATUS

approved



