18560

Appears in sequences

• Narayana's cows sequence: a(0) = a(1) = a(2) = 1; thereafter a(n) = a(n-1) + a(n-3).at n=27A000930
• Theta series of {D_6}* lattice.at n=51A008425
• Longest edge a of smallest (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).at n=27A031173
• Pisot sequence P(4,6).at n=22A048625
• Pisot sequence P(6,9).at n=21A048626
• Expansion of (1-x)^2/(1 - 4*x + 3*x^2 - x^3).at n=9A052544
• n*10^3-1, n*10^3-3, n*10^3-7 and n*10^3-9 are all prime.at n=11A064977
• Number of ways to tile a 2 X n room with 1 X 2 Tatami mats. At most 3 Tatami mats may meet at a point.at n=26A068921
• Expansion of 1/(1+2*x^2-2*x^3).at n=21A077964
• a(n) = a(n-1) + a(n-3) for n >= 3, with a(0) = 1, a(1) = a(2) = 0. This recurrence can also be used to define a(n) for n < 0.at n=30A078012
• Expansion of (1-x)/(1+2*x+2*x^2+2*x^3).at n=22A078071
• Sequence A000930 with terms repeated.at n=54A108104
• Sequence A000930 with terms repeated.at n=55A108104
• a(n) = n-1, if n <= 2, otherwise A107458(n-1) + A107458(n-2).at n=32A135851
• a(0) = 0, a(1) = 1, a(2) = 2; for n > 2, a(n) = a(n-1) + 2*a(n-2) + a(n-3).at n=14A141015
• a(n) = Sum_{k=1..n} b(k)*a(n - k) for n >= 1, where b(n) = b(n-2) + b(n-3) for n >= 3 with b(0) = 0 and b(1) = b(2) = 1.at n=14A141683
• 1 followed by A141015.at n=15A142474
• Numbers with prime signature {7,1,1}, i.e., of form p^7*q*r with p, q and r distinct primes.at n=24A179696
• Number of 3-step left-handed knight's tours (moves only out two, left one) on an n X n board summed over all starting positions.at n=41A187173
• Molecular topological indices of the sunlet graphs.at n=19A192846