20705

Appears in sequences

• Lucas-Carmichael numbers: squarefree composite numbers k such that p | k => p+1 | k+1.at n=10A006972
• Generalized Catalan numbers A(x)^2 -(1+x)^2*A(x) +x*(2+x+x^2) =0.at n=12A025242
• Expansion of (1 + x^2 - sqrt( 1 - 4*x + 2*x^2 + x^4)) / (2*x) in powers of x.at n=12A082582
• Number of Dyck paths of semilength n with no DDUU.at n=11A086581
• Triangle read by rows: T(n,k) is number of Dyck n-paths with k UUDDs, 0 <= k <= n/2.at n=42A098978
• Lucas-Carmichael numbers that are not congruent to 11 (mod 12).at n=2A110885
• a(n) = numerator of sum of reciprocals of the terms of the continued fraction for H(n) = Sum_{k=1..n} 1/k.at n=16A112286
• Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n and having k DDUU's, where U=(1,1), D=(1,-1) (0<=k<=floor(n/2)-1 for n>=2).at n=27A114492
• Numbers k such that k^3 divides 4^(k^2) + 1.at n=4A128678
• Numbers k such that 16 plus the k-th triangular number is a perfect square.at n=10A154146
• Lucas-Carmichael numbers with 3 prime factors.at n=8A216925
• Number of cyclotomic cosets of 7 mod 10^n.at n=17A220019
• Least k such that the sum of the semiprime divisors equals n times the sum of the prime divisors, or 0 if no such k exists.at n=31A227419
• Number T(n,k) of Dyck paths of semilength n having exactly k (possibly overlapping) occurrences of the consecutive step pattern given by the binary expansion of n, where 1=U=(1,1) and 0=D=(1,-1); triangle T(n,k), n>=0, read by rows.at n=51A243752
• Number of Dyck paths of semilength n avoiding the consecutive step pattern given by the binary expansion of n, where 1=U=(1,1) and 0=D=(1,-1).at n=12A243754
• Least Lucas-Carmichael number divisible by the n-th prime.at n=11A253597
• Least Lucas-Carmichael number divisible by the n-th prime.at n=24A253597
• a(n) = least Lucas-Carmichael number which is divisible by b(n), where {b(n)} (A255602) is the list of all numbers which could be a divisor of a Lucas-Carmichael number.at n=15A253598
• a(n) = least Lucas-Carmichael number which is divisible by b(n), where {b(n)} (A255602) is the list of all numbers which could be a divisor of a Lucas-Carmichael number.at n=34A253598
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 225", based on the 5-celled von Neumann neighborhood.at n=31A270944