66681

Appears in sequences

• Berend Jan van der Zwaag's conjectured complete list of numbers that start different "expanding periodic loops" under the mapping described in A053392 and A060630.at n=22A103117
• Numbers k such that the k-th triangular number contains only digits {1,2,3}.at n=14A119098
• Number of 2 X 2 matrices having all terms in {-n,...,0,...,n} and nonnegative determinant.at n=9A211147
• G.f. A(x) satisfies (3*A(x^9)/A(x) - 1)^3 = 9*A(x^3)^3/A(x)^3 - 1 - 9*x.at n=7A376528
• Numbers that can be written in exactly two different ways in the form described by A387302.at n=13A387898