20476

Appears in sequences

• Sum of logarithmic numbers.at n=7A002744
• Number of numbers of complexity n, i.e., that can be built from n ones using + and *, and require at least that many ones.at n=33A005421
• a(n) = T(4,n), array T given by A048483.at n=12A048487
• Smallest n-aspiring number. That is, a(n) = smallest k such that s^(n)(k) is perfect but s^(n-1)(k) is not, where s(k) is the sum of the aliquot parts of k and s^(i) means iterate s i times.at n=14A099771
• Numbers k such that tau(k) = tau(k+1) mod 691, where tau is Ramanujan's tau function A000594.at n=31A121733
• Start with 1, then alternately add 2 or double.at n=24A123208
• Binomial transform of [1, 0, 0, 4, 0, 0, 7, 0, 0, 10, ...].at n=13A139545
• a(n) = 1 + (6 + (11 + (6 + n)*n)*n)*n/24.at n=25A145126
• Expansion of (2/(3*sqrt(1-4*z)-1+4*z))*((1-sqrt(1-4*z))/(2*z))^k with k=7.at n=6A172064
• Number of strings of numbers x(i=1..5) in 0..n with sum i^3*x(i) equal to 125*n.at n=38A184260
• Partial sums of A200675.at n=48A200678
• Number of unimodal maps [1..n]->[0..3].at n=13A223659
• a(n) is one fourth of the total number of free ends of 4 line segments expansion at n iterations (see Comments lines for definition).at n=24A238549
• Numbers n such that triangular numbers T(n), T(n+1) and T(n+2) are 3-almost primes.at n=12A255200
• Start at a(0)=1. a(n) = a(n-1)+2 if n == 1,2 (mod 3) and a(n)=a(n-1)+a(n-3) if n == 0 (mod 3).at n=36A268896
• Expansion of (x - x^2 + 2*x^3 + 2*x^4)/(1 - 3*x + 2*x^2).at n=14A270810
• Triangle read by rows: T(n,k) = number of configurations of k nonattacking bishops on the black squares of an n X n chessboard (0 <= k <= n - [n>1]).at n=43A274105
• Sum of cubes of proper divisors of n.at n=47A276634
• a(n) = PrimePi(A246033(n)) (where PrimePi = A000720).at n=45A290652
• Numbers k such that 337*2^k+1 is prime.at n=18A322961