18580

Appears in sequences

• a(n) = C(n+2,3) + C(n,3) + C(n-1,3).at n=33A006004
• Numbers k such that h(k) = h(k-1) + h(k-2), where h(k) = A006577(k) + 1 is the length of the sequence {k, f(k), f(f(k)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=31A078418
• Numbers n such that h(n) = 2 h(n-1) where h(n) is the length of the sequence {n, f(n), f(f(n)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=35A078419
• A089450 indexed by A000040.at n=14A089525
• Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1), U=(1,2), or d=(1,-1) and having abscissa of first return equal to 3k.at n=25A108439
• Sum of squares of four consecutive primes.at n=17A133524
• Numbers n such that 10^n - 51 is prime.at n=8A178429
• The number of 1-length gaps in all possible covers of n-length line by 2-length segments.at n=30A228577
• Value of concatenation of all suffixes of binary representation of n.at n=18A241426
• Expansion of Product_{k>=1} 1/(1 - k^4*x^k).at n=6A265838
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 453", based on the 5-celled von Neumann neighborhood.at n=30A272275
• Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of Product_{j>=1} 1/(1 - j^k*x^j).at n=61A292193
• Number of unlabeled oriented edge-rooted 2-trees which have n triangles.at n=10A303742
• Array read by antidiagonals: T(n,k) is the number of unlabeled oriented k-gonal 2-trees with n oriented polygons, n >= 0, k >= 2.at n=76A340812
• Irregular table read by rows, T(n, k) is the rank of the k-th Seidel permutation of {1,...,n}, permutations sorted in lexicographical order.at n=34A347600
• Number of integer partitions of n such that it is not possible to choose a different constant integer partition of each part.at n=37A387329