A392053 - OEIS

%I #13 Jan 31 2026 19:16:02

%S 1,16,2943,3870,24993,50327950,50330650,346452825,390696875,401044425,

%T 401045325

%N Numbers k such that sigma(k) = psi(k) + pi(k) + omega(k)^4.

%e 2943 is a term since sigma(2943) = 4400 = 3960 + 424 + 2^4 = psi(2943) + pi(2943) + omega(2943)^4.

%o (PARI) dedpsi(f) = prod(k = 1, #f~, (f[k, 1]+1) * f[k, 1]^(f[k, 2]-1));

%o list(lim) = {my(q = 2, m = 0, f); print1(1, ", "); forprime(p = 3, lim, m++; for(k = q, p-1, f = factor(k); if(sigma(f) == dedpsi(f) + m + omega(f)^4, print1(k, ", "))); q = p);} \\ _Amiram Eldar_, Jan 26 2026

%Y Cf. A000203, A000720, A001615, A001221, A390234, A390235, A390236.

%K nonn,hard,more

%O 1,2

%A _S. I. Dimitrov_, Jan 26 2026

%E a(8)-a(11) from _Amiram Eldar_, Jan 26 2026