37950

Appears in sequences

• Number of unrooted triangulations of a disk with 2 internal nodes and n+3 nodes on the boundary.at n=8A005504
• Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n+2)/3.at n=30A048079
• Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n+3)/3.at n=30A048090
• Tritriangular numbers: a(n) = binomial(binomial(n,2),2) = n*(n+1)*(n-1)*(n-2)/8.at n=24A050534
• McKay-Thompson series of class 15A for Monster.at n=19A058508
• Triangular numbers which are products of triangular numbers larger than 1.at n=30A068143
• Triangular numbers which are 6-almost primes.at n=25A076580
• Numbers of the form prime(n) + prime(n+1) - 2 that are also triangular numbers, T(k) = k(k+1)/2.at n=25A110891
• Triangular numbers whose digit reversal is the product of 2 palindromes greater than 1.at n=33A115702
• Triangular numbers that are the product of 2 palindromes greater than 1.at n=29A115744
• A123689 based sequence as SO(A123689(n)) dimensions.at n=18A131513
• McKay-Thompson series of class 15A for the Monster group with a(0) = 1.at n=19A134783
• McKay-Thompson series of class 15A for the Monster group with a(0) = 4.at n=19A153765
• Triangular numbers t such that all the digits needed to write the consecutive triangular numbers from 0 to t fill exactly an equilateral triangle (no holes, no overlaps).at n=19A158030
• a(n) = smaller member of n-th pair of distinct, positive, triangular numbers whose sum and difference are also triangular numbers.at n=13A185129
• Triangular numbers T from A000217 such that (4*T+1)/13 is prime.at n=15A208294
• G.f.: 1/(1-x) = Sum_{n>=0} a(n)*x^n*Product_{k=1..n+1} (1-x^k).at n=32A209405
• Triangular numbers that are the product of three distinct triangular numbers greater than 1.at n=13A225440
• Sequence of distinct least triangular numbers such that the arithmetic mean of the first n terms is also a triangular number. Initial term is 0.at n=24A236415
• Triangular numbers which have one or more occurrences of exactly five different digits.at n=27A241788