210027483919domain: NAppears in sequencesa(n) = n^9 + n^8 + n^7 + n^6 + n^5 + n^4 + n^3 + n^2 + n + 1.at n=18A103623a(n) = (18^n-1)/17.at n=10A218721a(n) = Sum_{k=0..n} (2*n)^k.at n=9A349961