18226

Appears in sequences

• Expansion of (1+x^3*C)*C, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108.at n=10A071726
• Number of compositions of n into twin primes (i.e., primes that are members of a twin prime pair, like 3, 5, 7, 11, 13, but not 2 or 23).at n=44A077608
• Smallest squarefree integer k such that Q(sqrt(k)) has class number n.at n=35A081363
• Diagonal in array of n-gonal numbers A081422.at n=25A081437
• Number of pairs with two different elements which can be obtained by selecting unique elements from two sets with n+1 and n^2 elements respectively and n common elements.at n=26A085490
• Second (k=2) triangle of numbers related to totally asymmetric exclusion process (case alpha=1, beta=1).at n=43A115127
• Numbers n such that n^24 + 1 = p*q with p,q distinct primes.at n=30A119982
• Triangle read by rows: A001263 * A128064 * A000012 as infinite lower triangular matrices.at n=51A136536
• Triangle read by rows, derived from a(n) = N*a(n-1) + a(n-2).at n=23A138765
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 0), (-1, 1, -1), (0, 0, 1), (1, 0, -1)}.at n=12A148002
• a(n) = 729*n + 1.at n=24A158397
• Numbers that are 4-digit palindromes in at least 2 bases.at n=23A180453
• Number of n X n 0..n-1 arrays with no column j greater than column j-1 in all rows.at n=2A212924
• Number of n X 3 0..2 arrays with no column j greater than column j-1 in all rows.at n=2A212925
• T(n,k) = number of n X k 0..k-1 arrays with no column j greater than column j-1 in all rows.at n=12A212930
• Number of 3 X n 0..n-1 arrays with no column j greater than column j-1 in all rows.at n=2A212932
• Smallest palindromic numbers of length 4 in two bases differing by n.at n=11A216843
• a(n) = floor(n!/3^n).at n=14A228448
• Numbers whose square is a fourth power plus a prime.at n=23A236767
• a(n) = Catalan(n) mod Fibonacci(n).at n=22A246846