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 A090329 #14 May 13 2025 08:25:12
%S A090329 0,1,1,2,1,2,1,3,1,3,1,4,1,2,2,4,1,4,1,4,2,3,1,6,1,2,2,4,1,5,1,5,1,3,
%T A090329 1,7,1,3,2,6,1,5,1,4,3,3,1,8,1,4,2,4,1,6,2,6,2,2,1,8,1,2,3,6,1,5,1,5,
%U A090329 1,5,1,9,1,3,2,5,1,6,1,8,2,3,1,8,2,3,2,6,1,7,1,4,2,3,2,10,1,3,2,6,1,6
%N A090329 Number of divisors of n that are prefixes of other divisors of n in binary representation.
%F A090329 a(p) = 1 for all primes p.
%F A090329 a(n) = A090330(n) + 1.
%e A090329 Divisors of n = 35: {1,5,7,35}, in binary {1,101,111,100011}: as only '1' is a prefix, a(35) = 1;
%e A090329 Divisors of n = 45: {1,3,5,9,15,45}, in binary {1,11,101,1001,1111,101101}: '1' is a prefix of all other divisors, '11' of '1111' and '101' of '101101', therefore a(45) = 3.
%Y A090329 Cf. A000005, A090330.
%K A090329 nonn,base
%O A090329 1,4
%A A090329 _Reinhard Zumkeller_, Nov 26 2003