82215

Appears in sequences

• Quadrinomial coefficients: C(2+n,n) + C(3+n,n) + C(4+n,n).at n=34A005718
• Tritriangular numbers: a(n) = binomial(binomial(n,2),2) = n*(n+1)*(n-1)*(n-2)/8.at n=29A050534
• Consider 2n tennis players; a(n) is the number of matches needed to let every possible pair play each other.at n=13A062346
• Triangular numbers which are products of triangular numbers larger than 1.at n=39A068143
• a(1) = 1; a(n) is the smallest triangular number > a(n-1) which differs from it at every digit.at n=35A068855
• a(1) = 0, then smallest triangular number such that a(n+1)- a(n) is a palindrome.at n=27A075057
• Triangular numbers which are 7-almost primes.at n=26A076581
• Triangle by rows T(n,k), showing the number of meanders with length (n+1)*4 and containing (k+1)*4 Ls and (n-k)*4 Rs, where Ls and Rs denote arcs of equal length and a central angle of 90 degrees which are positively or negatively oriented.at n=25A197653
• Triangular numbers whose binary conversion, read in decimal, is prime.at n=14A227028
• Triangle read by rows: T(n,k) is the number of quasi series-parallel matroids on [n] with rank k, 0 <= k <= n.at n=39A359985
• Triangle read by rows: T(n,k) is the number of quasi series-parallel matroids on [n] with rank k, 0 <= k <= n.at n=41A359985