cp's OEIS Frontend

A066772 Continued fraction expansion for Sum_{k>=1} d(k)/2^k where d(k) are divisors of k, 1 <= d <= k.

%I A066772 #25 Jul 04 2024 15:36:02
%S A066772 2,1,2,1,9,1,2,1,1,1,5,8,1,3,2,3,2,2,2,2,1,3,3,4,12,1,1,1,11,4,15,6,3,
%T A066772 3,2,1,20,4,4,1,4,1,2,1,2,6,1,2,1,28,107,1,4,4,3,1,2,2,4,2,3,51,1,1,1,
%U A066772 4,2,4,1,20,20,1,14,3,27,1,4,3,14,329,1,1,1,111,2,3,1,2,1,4,1,6,1,4,1
%N A066772 Continued fraction expansion for Sum_{k>=1} d(k)/2^k where d(k) are divisors of k, 1 <= d <= k.
%C A066772 A(1669) accurate to 500 decimal digits.
%D A066772 Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 354-361.
%H A066772 Steven R. Finch, <a href="http://www.people.fas.harvard.edu/~sfinch/constant/dig/dig.html">Digital Search Tree Constants</a> [Broken link]
%H A066772 Steven R. Finch, <a href="http://web.archive.org/web/20010413214937/http://www.mathsoft.com:80/asolve/constant/dig/dig.html">Digital Search Tree Constants</a> [From the Wayback machine]
%o A066772 (PARI) {smv(v)= s=0; for(i=1,matsize(v)[2],s=s+v[i]); s }
%o A066772 {A066766(n)= sm=0; for(j=1,n,sm=sm+smv(divisors(j)/2^j)); sm*1.0 }
%o A066772 (PARI) contfrac(suminf(k=1, sigma(k)/2^k)) \\ _Michel Marcus_, Apr 25 2022
%Y A066772 Cf. A066766 (decimal expansion).
%K A066772 nonn,cofr
%O A066772 0,1
%A A066772 _Randall L Rathbun_, Jan 16 2002
%E A066772 Offset changed by _Andrew Howroyd_, Jul 04 2024