Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #6 Sep 05 2020 18:55:38
%S 7,8,10,7,13,10,13,12,12,12,8,9,18,9,17,13,8,16,7,17,9,7,19,8,9,7,17,
%T 18,16,9,23,7,10,18,16,16,6,24,9,21,15,9,13,19,17,22,15,17,26,15,9,15,
%U 9,17,22,9,29,9,23,19,9,15,16,9,14,28,17,11,17,25,17,23,14,22,9,14,25,16,16,31,17,15,15,11,20
%N a(n) = A080224(A337386(n)).
%H Antti Karttunen, <a href="/A337468/b337468.txt">Table of n, a(n) for n = 1..20000</a>
%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F a(n) = A080224(A337386(n)).
%o (PARI)
%o A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
%o isA337386(n) = { my(x=A003961(n)); (sigma(x)>=2*x); };
%o A080224(n) = sumdiv(n, d, sigma(d)>2*d)
%o k=0; for(n=1,2^12,if(isA337386(n),print1(A080224(n),", ")));
%Y Cf. A000203, A003961, A003973, A080224, A337386.
%K nonn
%O 1,1
%A _Antti Karttunen_, Sep 01 2020