Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + … + d_(2)*10 + d_(1). Sequence lists the numbers n such that Sum_{i=1..k-1}{phi(Sum_{j=1..i}{d_(j)*10^(j-1)})} = Sum_{i=1..k-1}{sigma(Sum_{j=1..i}{d_(k-j+1)*10^(i-j)})} (see example below).
A244069
Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + … + d_(2)*10 + d_(1). Sequence lists the numbers n such that Sum_{i=1..k-1}{phi(Sum_{j=1..i}{d_(j)*10^(j-1)})} = Sum_{i=1..k-1}{sigma(Sum_{j=1..i}{d_(k-j+1)*10^(i-j)})} (see example below).
Terms
- a(0) =11a(1) =21a(2) =53a(3) =75a(4) =83a(5) =95a(6) =211a(7) =506a(8) =523a(9) =708a(10) =908a(11) =932a(12) =955a(13) =1008a(14) =5086a(15) =6535a(16) =7272a(17) =7557a(18) =9126a(19) =20534a(20) =31165a(21) =51301a(22) =52695a(23) =71665a(24) =73713a(25) =85173a(26) =90902a(27) =93026a(28) =93565a(29) =210021
External references
- oeis: A244069