

A274173


Numbers n such that n is not divisible by 5 and n^k is of the form a^2 + b^4 for all k not divisible by 4.


0




OFFSET

1,1


COMMENTS

Numbers n such that n, n^2 and n^3 is in A111925 and n is not divisible by 5.
Since there cannot be fourth power in A111925, this sequence focuses on the values of k that is not divisible by 4 in definition.


LINKS

Table of n, a(n) for n=1..4.


EXAMPLE

609076 is a term because 609076 = 710^2 + 18^4, 609076^2 = 581940^2 + 424^4, 609076^3 = 475342920^2 + 676^4 and it is not divisible by 5.


PROG

(PARI) isA111925(n) = for(b=1, sqrtnint(n1, 4), if(issquare(nb^4), return(1))); 0;
isok(n) = n%5 != 0 && isA111925(n) && isA111925(n^2) && isA111925(n^3);


CROSSREFS

Cf. A111925.
Sequence in context: A184561 A321705 A218107 * A206175 A205429 A308279
Adjacent sequences: A274170 A274171 A274172 * A274174 A274175 A274176


KEYWORD

nonn,more


AUTHOR

Altug Alkan, Jun 12 2016


STATUS

approved



