Least k such that sigma(k)=m^n for some m>1.

Terms

a(0) =2a(1) =3a(2) =7a(3) =217a(4) =21a(5) =2667a(6) =93a(7) =217a(8) =381a(9) =651a(10) =2752491a(11) =2667a(12) =8191a(13) =11811a(14) =24573a(15) =57337a(16) =82677a(17) =172011a(18) =393213a(19) =761763a(20) =1572861a(21) =2752491a(22) =5332341a(23) =11010027a(24) =21845397a(25) =48758691a(26) =85327221a(27) =199753347a(28) =341310837a(29) =677207307