A226832 Numbers of the form 8^j + 9^k, for j and k >= 0.

2, 9, 10, 17, 65, 73, 82, 89, 145, 513, 521, 593, 730, 737, 793, 1241, 4097, 4105, 4177, 4825, 6562, 6569, 6625, 7073, 10657, 32769, 32777, 32849, 33497, 39329, 59050, 59057, 59113, 59561, 63145, 91817, 262145, 262153, 262225, 262873, 268705, 321193, 531442

Offset: 1

Author

T. D. Noe, Jun 19 2013

Keywords

• nonn

Links

• T. D. Noe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A004050 (2^j + 3^k), A226806-A226831 (cases to 7^j + 9^k).

Programs

Mathematica

a = 8; b = 9; mx = 600000; Union[Flatten[Table[a^n + b^m, {m, 0, Log[b, mx]}, {n, 0, Log[a, mx - b^m]}]]]

PARI

ispowof(n,k)=k^valuation(n,k)==n
is(n)=if(n%8 != 1, return(ispowof(n-1,9))); for(k=0,logint(n-1,9), if(ispowof(n-9^k,8), return(1))); 0 \\ Charles R Greathouse IV, Aug 29 2016