40005

Appears in sequences

• Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 80.at n=4A031758
• Multiples of 9 in which there is no common digit in successive terms.at n=29A083497
• Odd numbers k such that abs(sigma(k)-2k) <= sqrt(k). Abundance-radius = abs(sigma(k)-2k) does not exceed square root of k and k is odd.at n=20A087415
• a(n) = 25*n^2 + 5.at n=39A158445
• a(n) = ((2^b-1)/phi(n))*Sum_{d|n} Moebius(n/d)*d^(b-1) for b = 4.at n=37A160892
• Powers of sqrt(5) - 1 rounded down.at n=49A179241
• a(n) = floor(4^n/((1+sqrt(5))/2)^(2*n)).at n=25A240523
• Number of (n+2)X(4+2) 0..1 arrays with every 3X3 subblock sum of the two sums of the diagonal and antidiagonal minus the two minimums of the central column and central row nondecreasing horizontally, vertically and ne-to-sw antidiagonally.at n=20A254903
• a(n) = (3/4) * Sum_{k>=0} (3*k)^n/4^k.at n=6A255927
• Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n) + 2*n, where a(0) = 1, a(1) = 2, b(0) = 3, b(1) = 4, b(2) = 5, and (a(n)) and (b(n)) are increasing complementary sequences.at n=17A294170
• Numbers m such that there are precisely 19 groups of order m.at n=22A298910
• Numbers equal to the sum of their aliquot parts, each of them increased by 6.at n=5A304278
• A(n, k) = A_{n}(k) where A_{n}(x) are the Eulerian polynomials, square array read by ascending antidiagonals, for n >= 0 and k >= 0.at n=61A326323
• A(n, k) = Sum_{j=0..n} j!*Stirling2(n, j)*(k-1)^(n-j), for n >= 0 and k >= 0, read by ascending antidiagonals.at n=59A332700
• Number of nonempty labeled antichains of subsets of [n] such that the largest subset is of size 2.at n=6A379706
• Triangle read by rows: T(n,k) is the number of nonempty labeled antichains of subsets of [n] such that the largest subset is of size k.at n=23A379712
• Numerator of (2^n - 1)*n! / 2^(n+1).at n=7A382709