42500
domain: N
Appears in sequences
- Denominators of Van der Pol numbers.at n=15A003163
- Numbers that are the sum of 2 nonzero squares in exactly 5 ways.at n=15A025288
- Numbers that are the sum of 2 distinct nonzero squares in exactly 5 ways.at n=11A025306
- a(n) = (1/sqrt(5))*((sqrt(5) + 1)*((15 + 5*sqrt(5))/2)^(n-1) + (sqrt(5) - 1)*((15 - 5*sqrt(5))/2)^(n-1)).at n=4A109106
- The common value of sigma_2 for square-amicable numbers, sigma_2(m)=sigma_2(n), m<n.at n=14A110929
- a(n) = (n^3 +n)*5^n.at n=3A128013
- Row sums of Riordan array ((1-3x+x^2)/(1-4x+3x^2), x(1-2x)/(1-4x+3x^2)).at n=9A147748
- Number of paths of length n starting at initial node of the path graph P_9.at n=18A178381
- Number of (w,x,y,z) with all terms in {1,...,n} and w*x+y*z>n^2.at n=26A212136
- a(n) = Sum_{0 < x,y,z <= n and gcd(x^2 + y^2 + z^2, n)=1} gcd(x^2 + y^2 + z^2 - 1, n).at n=24A239612
- Numbers k such that 6*5^k - 1 is prime.at n=23A257790
- Magic sums of 4 X 4 magic squares composed of odd squares.at n=17A271582
- Numbers that are the sum of 2 squares in exactly 5 ways.at n=23A294716
- a(n) = n*(6*n^4 + 8*n^3 + 1 - (-1)^n)/16.at n=10A374709