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%I #9 Jan 15 2019 18:46:09
%S 1,9,65,73,513,585,4097,4161,4681,32769,37449,262145,262657,266305,
%T 299593,2097153,2396745,16777217,16781313,17043521,19173961,134217729,
%U 134480385,153391689,1073741825,1073774593,1090785345,1227133513,8589934593,9817068105
%N Numbers of the form (8^{mr}-1)/(8^r-1) for positive integers m, r.
%C Numbers which in base 8 contain only 0's and 1's, with equally spaced 1's. - _Robert Israel_, Jan 15 2019
%H Robert Israel, <a href="/A076287/b076287.txt">Table of n, a(n) for n = 1..7932</a>
%H T. Chinburg and M. Henriksen, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa29/aa2932.pdf">Sums of k-th powers in the ring of polynomials with integer coefficients</a>, Acta Arithmetica, 29 (1976), 227-250.
%p 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
%Y 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).
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Nov 06 2002