A337468 - 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