cp's OEIS Frontend

A342921 a(n) = A003415(A019565(n)).

%I A342921 #16 Apr 09 2021 09:22:18
%S A342921 0,1,1,5,1,7,8,31,1,9,10,41,12,59,71,247,1,13,14,61,16,87,103,371,18,
%T A342921 113,131,493,167,719,886,2927,1,15,16,71,18,101,119,433,20,131,151,
%U A342921 575,191,837,1028,3421,24,191,215,859,263,1241,1504,5153,311,1623,1934,6871,2556,10117,12673,40361,1,19,20,91,22,129
%N A342921 a(n) = A003415(A019565(n)).
%H A342921 Antti Karttunen, <a href="/A342921/b342921.txt">Table of n, a(n) for n = 0..8192</a>
%H A342921 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%F A342921 a(n) = A003415(A019565(n)) = A069359(A019565(n)).
%F A342921 a(n) = A327860(A276156(n)) = A329029(A276156(n)) = A342002(A276156(n)).
%t A342921 Array[If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]]] &[Times @@ Prime@ Flatten@ Position[Reverse@ IntegerDigits[#, 2], 1]] &, 70, 0] (* _Michael De Vlieger_, Apr 08 2021 *)
%o A342921 (PARI)
%o A342921 A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
%o A342921 A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
%o A342921 A342921(n) = A003415(A019565(n));
%Y A342921 Cf. A003415, A019565, A069359, A276156, A327860, A329029, A342002.
%K A342921 nonn,look
%O A342921 0,4
%A A342921 _Antti Karttunen_, Apr 06 2021