900900990991domain: NAppears in sequencesCyclotomic polynomials at x=10.at n=20A019328Primitive cofactor of n-th repunit A002275(n).at n=20A204847a(n) = n^12 - n^11 + n^9 - n^8 + n^6 - n^4 + n^3 - n + 1.at n=10A269483