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A074936
Number of perfect powers between two successive nonprime prime powers.
0
0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 3, 0, 0, 1, 0, 3, 0, 1, 1, 1, 1, 1, 4, 0, 3, 2, 2, 1, 0, 0, 1, 4, 2, 4, 1, 2, 2, 3, 0, 1, 6, 1, 1, 0, 6, 2, 7, 3, 1, 4, 1, 1, 2, 8, 3, 1, 0, 1, 1, 6, 1, 1, 9, 1, 5, 0, 5, 4, 1, 3, 0, 5, 1, 0, 10, 1, 3, 2, 12, 11, 2, 1, 1, 3
OFFSET
1,15
LINKS
Eric Weisstein's World of Mathematics, Perfect Power.
Eric Weisstein's World of Mathematics, Prime Power.
EXAMPLE
There are three perfect powers with composite roots between A025475(15)=169=13^2 and A025475(15+1)=243=3^5: 196=(2*7)^2, 216=3^5 and 225=(3*5)^2; therefore a(15)=3.
a(16)=0, since there are no perfect powers between A025475(16)=243=3^5 and A025475(16+1)=256=2^8.
CROSSREFS
Sequence in context: A331509 A171913 A342154 * A035655 A353323 A239446
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 10 2002
STATUS
approved