51156

Appears in sequences

• 4-dimensional pyramidal numbers: a(n) = n^2*(n^2-1)/12.at n=28A002415
• Denominators of continued fraction convergents to sqrt(925).at n=9A042789
• Numbers k such that 3*7^k - 2 is prime.at n=12A059091
• Triangle read by rows: matrix inverse of A154959.at n=23A154960
• Triangle T(n, k) = n! * binomial(n, k)*( psi(n-k+1) - psi(k+1) ), read by rows.at n=29A157521
• a(n) = n^2 * (4*n^2 - 1) / 3.at n=14A187756
• Numbers with prime factorization pq^2r^2s^2.at n=27A189344
• Numbers k such that k and k^3 are sums of two twin primes.at n=17A213811
• The Wiener index of the linear phenylene with n hexagons.at n=13A224454
• Nonsquare numbers whose sum of proper square divisors is a square greater than 1.at n=16A232555
• Numbers whose sum of proper square divisors is a square greater than 1.at n=19A232556
• Number of nX2 nonnegative integer arrays with upper left 0 and lower right n+2-5 and value increasing by 0 or 1 with every step right or down.at n=15A252970
• Triangle read by rows: T(n, k) = [x^k] (n*x + 1)*Hypergeometric([-n, -n + 1], [1], x).at n=49A371401
• a(n) = Sum_{k=0..floor(n/3)} binomial(k+2,2) * binomial(k,n-3*k)^2.at n=26A377147
• Triangle read by rows: T(n,k) = binomial(n+1,k+1) * binomial(5*n-4*k+1,k) / (n+1), 0<=k<=n.at n=39A391048
• Cubefree exponential abundant numbers: cubefree numbers k for which A051377(k) > 2*k.at n=36A391427