21658

Appears in sequences

• Sum of adjacent Catalan numbers.at n=9A005807
• Coordination sequence for {A_6}* lattice.at n=7A008534
• Concatenate rows of triangle in A028364 (removing duplicates).at n=47A028378
• (Terms in A029613)/2.at n=30A051435
• (Terms in A029627)/2.at n=46A051457
• Third diagonal of array in A059347.at n=18A059348
• Expansion of (1+x^2*C)*C, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108.at n=10A071716
• Tetranacci numbers starting with first four squares.at n=14A093175
• Self-convolution of repeated Catalan numbers.at n=18A104722
• Second (k=2) triangle of numbers related to totally asymmetric exclusion process (case alpha=1, beta=1).at n=44A115127
• The matrix-vector product A133566 * A000108.at n=10A133603
• Expansion of (1+x)*c(x), c(x) the g.f. of A000108.at n=10A167422
• Numbers k which use half of the ten digits such that they have at least one factorization k=p*q that uses remaining half of the digits that are not in k.at n=8A195814
• Number of words w where each letter of the n-ary alphabet occurs 10 times and for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.at n=2A213870
• Degrees of irreducible representations of simple Chevalley group F4(2).at n=6A214481
• Numbers n = p * q, where n, p, and q together contain all 10 digits at least once.at n=9A253172
• Values n, where n = p * q, and n, p, and q together contain all 10 digits at least once, and no digit is in more than one of n, p or q.at n=8A253173
• a(n) = cpg(n, 3) + cpg(n, 4) + ... + cpg(n, n) where cpg(n, m) is the m-th n-th-order centered polygonal number.at n=19A257051
• Triangle A106534 with reversed rows.at n=56A280470
• Number of 3 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=13A281207