44850

Appears in sequences

• Tritriangular numbers: a(n) = binomial(binomial(n,2),2) = n*(n+1)*(n-1)*(n-2)/8.at n=25A050534
• Numbers k such that 3*7^k + 2 is prime.at n=20A059041
• Consider 2n tennis players; a(n) is the number of matches needed to let every possible pair play each other.at n=11A062346
• Smallest triangular number which is a multiple (>1) of the n-th triangular number.at n=24A068084
• Triangular numbers with sum of digits = 21.at n=29A068131
• Triangular numbers which are 6-almost primes.at n=26A076580
• Triangular numbers m such that A040115(m) is also triangular.at n=24A087597
• Column 5 of triangle A091602.at n=49A091608
• Triangular numbers for which the sum of the digits is an octagonal number.at n=32A117523
• Minimal covering numbers.at n=30A160559
• Triangular numbers which are sums of 6 consecutive primes.at n=7A173423
• Triangular numbers which are an average of four consecutive primes.at n=25A226196
• Triangle read by rows: the reversed x = 1+q Narayana triangle at m=3.at n=23A243663
• Number of binary strings of length n that avoid the pattern x x^R x (x^R is the reversal of x).at n=35A261204
• Number of irreducible polynomials in the n-th generation of polynomials generated as in Comments.at n=13A264293
• Number of possible plugboard settings for a WWII German Enigma Cipher Machine with n cables.at n=2A266365
• Unitary practical numbers that are nonsquarefree.at n=33A287173
• Total number of binary digits in all partitions of n into distinct parts.at n=46A319140
• Triangle read by rows: T(n,k) is the number of trees with n leaves of exactly k colors and all non-leaf nodes having degree 3.at n=41A339650
• Triangular numbers T(i) that can be expressed as the sum of 2 positive triangular numbers, T(j)+T(k), and for which i+j+k is a triangular number, where T is A000217.at n=6A343426