A341611 - OEIS

%I #8 Feb 25 2021 16:57:41

%S 8,16,27,28,32,44,45,50,52,63,64,68,75,76,81,92,98,99,105,110,116,117,

%T 124,128,130,135,136,147,148,152,153,154,164,165,170,171,172,175,182,

%U 184,188,189,190,195,207,212,225,230,231,232,236,238,243,244,245,248,250,255,256,261,266,268,273,279,284,285,290,292,296,297

%N Nonabundant numbers that are not primitive terms of A246282.

%C Terms k of A263837 for which A337345(k) > 1 (or equally, for which A337346(k) > 0).

%C Numbers k such that sigma(k) <= 2k and k has at least two distinct divisors d such that 2d < A003961(d). By necessity, one of these divisors is then k itself.

%o (PARI)

%o A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };

%o A337345(n) = sumdiv(n,d,A003961(d)>(d+d));

%o isA341611(n) = ((sigma(n)<=(2*n))&&(1<A337345(n)));

%Y Intersection of A341610 and A263837. Subsequence of A341614.

%Y Cf. A000203, A003961, A337345, A337346.

%K nonn

%O 1,1

%A _Antti Karttunen_, Feb 22 2021