19323

Appears in sequences

• Expansion of 1/(1 - 3*x*C(x)), where C(x) = (1 - sqrt(1 - 4*x))/(2*x) = g.f. for the Catalan numbers A000108.at n=7A007854
• Numerators of continued fraction convergents to sqrt(773).at n=7A042490
• p^2 + 2 where p is a prime.at n=33A061725
• Square array read by antidiagonals: T(n,k)=(T(n,k-1)*n^2-Catalan(k-1)*n)/(n-1) with a(n,0)=1 and a(1,k)=Catalan(k) where Catalan(k)=C(2k,k)/(k+1)=A000108(k).at n=58A067347
• Numbers n such that (n+j) mod (2+j) = 1 for j from 0 to 6 and (n+7) mod 9 <> 1.at n=15A096025
• Riordan array (1/(1-3x*c(x)),xc(x)), c(x) the g.f. of A000108.at n=28A117375
• A129027(n)/4.at n=9A129028
• 9 times pentagonal numbers: 9*n*(3*n-1)/2.at n=38A152996
• Number of partitions of n*(n+1)/2 with at most four parts that can be obtained from grouping (with parentheses) a permutation of the sum 1+2+...+n.at n=16A160438
• Triangle read by rows: T(n,0) = 3^n, T(n,k) = T(n,k-1) + T(n-1,k) for 0 < k < n, and T(n,n) = T(n,n-1).at n=34A165992
• Triangle read by rows: T(n,0) = 3^n, T(n,k) = T(n,k-1) + T(n-1,k) for 0 < k < n, and T(n,n) = T(n,n-1).at n=35A165992
• a(n) is the smallest number which has in its English name the letter "n" in the n-th position beginning the count from the end.at n=38A173204
• Number of partitions of 3n + 2 into parts >= 3.at n=18A182808
• The number of disconnected k-regular simple graphs on 2k+4 vertices.at n=53A184324
• Starts of runs of 3 consecutive integers whose exponent of least prime factor in their prime factorization is even.at n=35A365871
• Number of fixed polyominoids with n cells, allowing right-angled corner-connections and any edge-connections.at n=3A366006
• Expansion of e.g.f. exp( (3/2) * (1-sqrt(1-4*x)) ).at n=5A369722