Odd numbers n such that sigma(n) = sigma(2*n-1).

Terms

a(0) =1a(1) =13545a(2) =57645a(3) =116865a(4) =1440495a(5) =7029855a(6) =8596455a(7) =27361125a(8) =41100345a(9) =48289185a(10) =56122185a(11) =77560065a(12) =103225185a(13) =134813385a(14) =146591235a(15) =163817745a(16) =188358885a(17) =198748305a(18) =242668335a(19) =269436375a(20) =352094715a(21) =358841385a(22) =535135965a(23) =563911335a(24) =636719265a(25) =712457655a(26) =724692045