A025623 Numbers of form 5^i*8^j, with i, j >= 0.

1, 5, 8, 25, 40, 64, 125, 200, 320, 512, 625, 1000, 1600, 2560, 3125, 4096, 5000, 8000, 12800, 15625, 20480, 25000, 32768, 40000, 64000, 78125, 102400, 125000, 163840, 200000, 262144, 320000, 390625, 512000, 625000, 819200, 1000000, 1310720

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

Sum_{n>=1} 1/a(n) = (5*8)/((5-1)*(8-1)) = 10/7. - Amiram Eldar, Sep 25 2020

a(n) ~ exp(sqrt(2*log(5)*log(8)*n)) / sqrt(40). - Vaclav Kotesovec, Sep 25 2020

Mathematica

n = 10^6; Flatten[Table[5^i*8^j, {i, 0, Log[5, n]}, {j, 0, Log[8, n/5^i]}]] // Sort (* Amiram Eldar, Sep 25 2020 *)

Crossrefs

Subsequence of A003592.

Sequence in context: A166652 A286571 A234334 * A069959 A038250 A067973

Adjacent sequences: A025620 A025621 A025622 * A025624 A025625 A025626

Keyword

easy,nonn

Author

David W. Wilson

Status

approved