21093

Appears in sequences

• Low-temperature susceptibility expansion for square lattice (Potts model, q=4).at n=8A057379
• Numbers k such that sigma(k+1) - sigma(k) = sigma(k)/d(k), where d(k) denotes the number of divisors of k.at n=9A066176
• Expansion of (1+x^2)*(1+x^5)*(1+x^8)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)*(1-x^5)*(1-x^6)*(1-x^7)*(1-x^8)*(1-x^9)*(1-x^10)).at n=34A069950
• a(n) = A108466(A025487).at n=33A108467
• Number of -4..4 arrays of n elements with first, second and third differences also in -4..4.at n=5A202120
• T(n,k) is the number of -k..k arrays of n elements with first, second and third differences also in -k..k.at n=41A202124
• Number of -n..n arrays of 6 elements with first, second and third differences also in -n..n.at n=3A202127
• Triangle of coefficients of polynomials u(n,x) jointly generated with A209169; see the Formula section.at n=51A209168
• Number of length 4 1..(n+1) arrays with every leading partial sum divisible by 2, 3, 5 or 7.at n=14A258635
• p-INVERT of the squares (A000290), where p(S) = 1 + S - 2 S^2.at n=6A292535
• Expansion of Product_{k>=1} (1 + x^k)^binomial(k+3,3).at n=8A343200
• Lower midsequence of the Fibonacci numbers (1,2,3,5,8,...) and Lucas numbers (1,3,4,7,11,...); see Comments.at n=20A355324