A336847 - OEIS

%I #7 Aug 06 2020 23:28:05

%S 0,2,4,12,6,12,10,36,30,28,12,72,16,36,44,120,18,122,22,102,68,52,28,

%T 120,54,60,152,150,30,168,36,362,80,76,92,402,40,84,104,312,42,264,46,

%U 156,246,108,52,720,132,222,100,216,58,600,84,456,140,124,60,612,66,148,366,1092,140,312,70,258,160,360,72

%N a(n) = A003973(n) - A336846(n).

%H Antti Karttunen, <a href="/A336847/b336847.txt">Table of n, a(n) for n = 1..16384</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) = A003973(n) - A336846(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 A336847(n) = { my(u=A003961(n),s=sigma(u)); (s-gcd(s, numdiv(n)*u)); };

%Y Cf. A000005, A000203, A003961, A003973, A336845, A336846, A336848.

%K nonn

%O 1,2

%A _Antti Karttunen_, Aug 06 2020