A318889 - OEIS

%I #7 Nov 22 2018 18:16:09

%S 0,1,0,2,0,5,0,4,1,7,0,10,0,9,3,8,0,17,0,14,3,13,0,20,2,15,6,18,0,33,

%T 0,16,5,19,4,34,0,21,3,28,0,43,0,26,17,25,0,40,2,37,5,30,0,53,6,36,3,

%U 31,0,66,0,33,19,32,4,63,0,38,5,61,0,68,0,39,28,42,6,73,0,56,25,43,0,86,6,45,7,52,0,111,4,50,3,49,4,80,0

%N a(n) = A001065(n) - A001065(A252463(n)).

%H Antti Karttunen, <a href="/A318889/b318889.txt">Table of n, a(n) for n = 1..16384</a>

%F a(n) = A001065(n) - A319699(n) = A001065(n) - A001065(A252463(n)).

%o (PARI)

%o A001065(n) = (sigma(n)-n);

%o A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};

%o A252463(n) = if(!(n%2),n/2,A064989(n));

%o A318889(n) = (A001065(n) - A001065(A252463(n)));

%Y Cf. A001065, A252463.

%Y Cf. also A319699, A319700, A319703, A319989, A320107, A320111.

%K nonn

%O 1,4

%A _Antti Karttunen_, Nov 22 2018