19400

Appears in sequences

• a(n) = n^2*(5*n-3)/2.at n=20A006597
• a(1) = 3; a(n+1) = a(n)-th nonprime, where nonprimes begin at 0.at n=41A025000
• Sums of 4 distinct powers of 5.at n=33A038476
• Sum of first n 8-almost primes.at n=15A086061
• a(1) = 1, otherwise a(n) = floor(e^(n+1)/(e^2 + 1)).at n=11A090039
• From the game of Quod: number of "squares" on an n X n array of points with the four corner points deleted.at n=20A124479
• Number of binary strings of length n with equal numbers of 00011 and 01100 substrings.at n=15A164231
• Partial sums of A048890.at n=17A172973
• G.f.: A(x) = Sum_{n>=0} x^n * C(x)^(n^2), where C(x) = 1 + x*C(x)^2 is the g.f. of the Catalan numbers (A000108).at n=8A183608
• Array: row n shows the coefficients of the characteristic polynomial of the n-th principal submatrix of the Delannoy matrix (A008288).at n=16A204135
• Relative of Hofstadter Q-sequence: a(n) = max(0, n+19395) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.at n=6A283886
• Number of non-isomorphic cyclic Haar graphs on 2*n nodes.at n=21A357000
• Expansion of 1/( 1 - Sum_{k>=0} x^(3^k) / (1 - x^(3^k)) ).at n=14A382367