This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A076275 #6 Jun 12 2015 20:06:10
%S A076275 1,5,17,21,65,85,257,273,341,1025,1365,4097,4161,4369,5461,16385,
%T A076275 21845,65537,65793,69905,87381,262145,266305,349525,1048577,1049601,
%U A076275 1118481,1398101,4194305,5592405,16777217,16781313,16843009,17043521,17895697,22369621
%N A076275 Numbers of the form (4^{mr}-1)/(4^r-1) for positive integers m, r.
%H A076275 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.
%Y A076275 Cf. A064896 (k=2), A076270 (k=3), A076284 (k=5), A076285 (k=6), A076286 (k=7), A076287 (k=8), A076288 (k=9), A076289 (k=10).
%K A076275 nonn
%O A076275 1,2
%A A076275 _N. J. A. Sloane_, Nov 06 2002