A076287 Numbers of the form (8^{mr}-1)/(8^r-1) for positive integers m, r.

1, 9, 65, 73, 513, 585, 4097, 4161, 4681, 32769, 37449, 262145, 262657, 266305, 299593, 2097153, 2396745, 16777217, 16781313, 17043521, 19173961, 134217729, 134480385, 153391689, 1073741825, 1073774593, 1090785345, 1227133513, 8589934593, 9817068105

Offset: 1

Author

N. J. A. Sloane, Nov 06 2002

Keywords

• nonn

Comments

Numbers which in base 8 contain only 0's and 1's, with equally spaced 1's. - Robert Israel, Jan 15 2019

Links

• Robert Israel, Table of n, a(n) for n = 1..7932
• T. Chinburg and M. Henriksen, Sums of k-th powers in the ring of polynomials with integer coefficients, Acta Arithmetica, 29 (1976), 227-250.

Crossrefs

Cf. A064896 (k=2), A076270 (k=3), A076275 (k=4), A076284 (k=5), A076285 (k=6), A076286 (k=7), A076288 (k=9), A076289 (k=10).

Programs

Maple

1, seq(seq((8^(k+r)-1)/(8^r-1), r = ListTools:-Reverse(sort(convert(numtheory:-divisors(k),list)))), k=1..20); # Robert Israel, Jan 15 2019