26378

Appears in sequences

• a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 1, 0, 2, 2.at n=15A025248
• a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5, with initial values 0,0,1,1.at n=26A025277
• Numbers which form a prime by appending a 3-digit odd number and form no primes by appending any 1- or 2-digit odd number not beginning with 0.at n=2A091089
• Select all integers from the list (p(k)-k)/tau(k), k>=1; p = A000041, tau = A000005.at n=19A141669
• Primefree centuries (i.e., numbers k such that no prime exists between 100*k and 100*k+99).at n=1A181098
• Number of ordered trees with n edges such that non-leaf vertices at even levels have outdegree 1 and those at odd levels have outdegree 2.at n=24A248100
• a(n) = the smallest number m such that gcd(sigma(m), pod(m)) = n where sigma(k) = the sum of the divisors of k (A000203) and pod(k) = the product of the divisors of k (A007955).at n=21A324527
• Ordered perimeters p of primitive Pythagorean triangles no side of which is squarefree.at n=43A329392
• Numbers which form a prime by appending a 3-digit number and form no primes by appending 1 digit or 2 digits.at n=1A365813
• Numbers whose sum of prime divisors equals the sum of square divisors.at n=18A390397