60605

Appears in sequences

• a(n) = 5*a(n-1) - a(n-2) for n > 1, a(0) = 0, a(1) = 1.at n=8A004254
• Denominators of continued fraction convergents to sqrt(21).at n=15A041033
• Triangle of Salie numbers.at n=40A065547
• Table by antidiagonals of T(n,k)=n*T(n,k-1)-T(n,k-2) starting with T(n,1)=1.at n=70A073134
• Triangular array A065547 unsigned and transposed.at n=40A085707
• Fifth column of Salié-triangle A065547.at n=4A095653
• Fifth in an infinite set of generalized Pascal's triangles, with trigonometric properties.at n=43A125078
• a(n) = the number of "isolated divisors" of n!. A positive divisor, k, of n is isolated if neither (k-1) nor (k+1) divides n.at n=20A133952
• Denominators in continued fraction [0; 1, 3, 1, 3, 1, 3, ...].at n=14A136211
• Triangle T(n,k) read by rows: coefficient of [x^k] of the polynomial p_n(x)=(5-x)*p_{n-1}(x)-p_{n-2}(x), p_0=1, p_1=5-x.at n=28A179900
• Triangle read by rows, antidiagonals of an array (r,k), r=(0,1,2,...), generated from 2 X 2 matrices of the form [1,r; 1,(r+1)].at n=62A179943
• Nonnegative values x of solutions (x, y) to the Diophantine equation x^2 + (x+84847)^2 = y^2.at n=34A201917
• Triangle of coefficients of Chebyshev's S(n,x+5) polynomials (exponents of x in increasing order).at n=28A207824
• Count of the first 10^n primes which do not contain the digit 4.at n=5A228416
• Recurrence equation: a(0) = 1 and a(n) = a(n-1)*sqrt(21*a(n-1)^2 + 4) for n >= 1.at n=3A230338
• T(n,k)=Number of (n+1)X(k+1) 0..1 arrays with every element equal to some horizontal or antidiagonal neighbor, with top left element zero.at n=34A232316
• Number of (7+1)X(n+1) 0..1 arrays with every element equal to some horizontal or antidiagonal neighbor, with top left element zero.at n=1A232323
• Numbers k such that A027998(k) is divisible by k.at n=9A304049
• Numbers k such that k and k+1 have at least 4 but not both exactly 4 distinct prime factors.at n=5A321494
• T(n,k) are the values of a variant of the Chebyshev polynomials P(n,x) of order n evaluated at x = k, where T(n,k), n >= 0, k <= n is a triangle read by rows. P(0,x) = 1, P(1,x) = x, P(n,x) = x*P(n-1,x) - P(n-2,x).at n=33A357892