cp's OEIS Frontend

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.

A188288 In lunar arithmetic in base 2, the number of divisors of the number 11...1101 (n digits, the binary expansion of 2^n-3).

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%I A188288 #42 Feb 22 2018 17:33:17
%S A188288 0,1,0,2,2,2,4,6,10,16,31,55,100,185,345,644,1209,2274,4298,8145,
%T A188288 15469,29454,56213,107489,205925,395190,759621,1462282,2818799,
%U A188288 5440705,10513994,20340794,39393580,76368240,148185145,287791544,559386196,1088144064,2118283567,4126561528,8044217224
%N A188288 In lunar arithmetic in base 2, the number of divisors of the number 11...1101 (n digits, the binary expansion of 2^n-3).
%C A188288 a(1)=1 by convention. The g.f. is only a conjecture.
%H A188288 N. J. A. Sloane, <a href="/A188288/b188288.txt">Table of n, a(n) for n = 0..255</a>
%H A188288 D. Applegate, M. LeBrun and N. J. A. Sloane, <a href="http://arxiv.org/abs/1107.1130">Dismal Arithmetic</a> [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
%H A188288 <a href="/index/Di#dismal">Index entries for sequences related to dismal (or lunar) arithmetic</a>
%F A188288 G.f.: x + x^3/(1-x) + Sum(x^l*(1-x)^2/(1-2*x+x^(l-1)-x^l+x^(l+2)), l=3..oo). - _N. J. A. Sloane_, Apr 19 2011
%e A188288 a(6) = 4 since 111101 has the divisors 1, 101, 1101, 111101.
%e A188288 a(8) = 10 since 11111101 has the divisors 1, 101, 1001, 1101, 10101, 11001, 11101, 111001, 111101, 11111101.
%Y A188288 Cf. A079500, A188524.
%K A188288 nonn,base
%O A188288 0,4
%A A188288 _Adam S. Jobson_ and _N. J. A. Sloane_, Mar 26 2011
%E A188288 a(1) in b-file corrected by _Andrew Howroyd_, Feb 22 2018