Numbers k such that the sets of prime factors (ignoring multiplicity) of A000203(k) = sigma(k) and of A001157(k) = sigma_2(k) are identical.

A081380

Numbers k such that the sets of prime factors (ignoring multiplicity) of A000203(k) = sigma(k) and of A001157(k) = sigma_2(k) are identical.

Terms

    a(0) =1a(1) =180a(2) =1444a(3) =12996a(4) =23805a(5) =36100a(6) =52020a(7) =60228a(8) =64980a(9) =68832a(10) =95220a(11) =301140a(12) =324900a(13) =344160a(14) =481824a(15) =1505700a(16) =1718721a(17) =1720800a(18) =2275758a(19) =2409120a(20) =3755844a(21) =6874884a(22) =6879645a(23) =7965153a(24) =8593605a(25) =11378790a(26) =12045600a(27) =15930306a(28) =17405892

External references