216513

Appears in sequences

• Numbers of the form 3^i*11^j.at n=37A003597
• Number of ways to add n ordinals.at n=14A005348
• Number of noninvertible 2 X 2 matrices over Z/nZ (determinant is a divisor of 0).at n=25A020479
• Odd numbers divisible by exactly 10 primes (counted with multiplicity).at n=4A046323
• Numbers k such that k divides 9^k + 8^k + 7^k.at n=19A057231
• Numbers k such that k | 4^k + 3^k + 2^k.at n=23A057238
• Ninth column of triangle A067417.at n=4A067424
• Second binomial transform of C(n+2,2).at n=9A081892
• G.f. defined as the limit: A(x) = lim_{n->oo} F(n)^(1/3^(n-1)) where F(n) is the n-th iteration of: F(0) = 1, F(n) = F(n-1)^3 + (3x)^((3^n-1)/2) for n >= 1.at n=11A101192
• Numbers k whose digits can be divided into two contiguous parts, k = concatenate(x, y), such that k = |x^2 - y^2|.at n=11A113797
• Riordan array (1/(1-3x),x(1-x)/(1-3x)^2).at n=46A114195
• a(n) = 11*3^n.at n=9A120354
• a(n) = 3^n*tetranacci(n) or (2^n)*A001648(n).at n=6A127220
• Numbers k which are concatenations k = x//y such that y^2 - x^2 = k.at n=7A162700
• (n-1)-st elementary symmetric function of the first n terms of the periodic sequence (3,1,3,1,3,1,3,1,...).at n=16A203231
• Number of 2 X 2 matrices having all terms in {1,...,n} and determinant = 0 (mod 3).at n=26A210698
• Number of 2 X 2 matrices having all elements in {0,1,...,n} and determinant = 0 (mod 3).at n=26A211033
• Triangle T(n,k) = k^n * sum(binomial(n,n-k-j),j=0..n-k).at n=31A215079
• Numbers having factorization Product_{i=1..m} p(i)^e(i) such that m > 1 and p(i) + e(i) is the same for each i.at n=30A219302
• a(n) = (n+1) * 3^(n-1).at n=9A288834