13250217

Appears in sequences

• a(n) = 2*A000129(n) - 1.at n=18A133654
• a(n)=a(n-1)+3a(n-2)+a(n-3).at n=20A137199
• The index of the first of two consecutive positive triangular numbers (A000217) the sum of which is equal to the sum of four consecutive positive triangular numbers.at n=8A262490