Numbers k with the property that it is possible to write the base 2 expansion of k as concat(a_2,b_2), with a_2>0 and b_2>0 such that, converting a_2 and b_2 to base 10 as a and b, we have sigma(a) + sigma (b) = sigma(k) - k.
A258813
Numbers k with the property that it is possible to write the base 2 expansion of k as concat(a_2,b_2), with a_2>0 and b_2>0 such that, converting a_2 and b_2 to base 10 as a and b, we have sigma(a) + sigma (b) = sigma(k) - k.
Terms
- a(0) =9a(1) =15a(2) =27a(3) =39a(4) =51a(5) =77a(6) =143a(7) =207a(8) =329a(9) =377a(10) =473a(11) =611a(12) =903a(13) =1241a(14) =1243a(15) =1273a(16) =1437a(17) =1591a(18) =2117a(19) =2303a(20) =2975a(21) =4189a(22) =8401a(23) =8657a(24) =11993a(25) =13849a(26) =15611a(27) =16771a(28) =18239a(29) =18599
External references
- oeis: A258813