420420

Appears in sequences

• a(n) = (5*n)!/((2*n)!*(2*n)!*n!).at n=3A001459
• Expansion of (1+6*x)/(1-4*x)^(7/2).at n=6A007744
• Areas of more than one primitive Pythagorean triangle.at n=9A024407
• a(n) = 14*(n+1)*binomial(n+5,8).at n=6A027813
• a(n) = 42*(n+1) * binomial(n+5,10).at n=4A027815
• T(n,k) = binomial(n,k)*binomial(n+k,k), 0 <= k <= n, triangle read by rows.at n=51A063007
• a(1)=1; for n > 0, a(n+1) = rad(a(n))*n where rad=A007947.at n=14A066332
• Gaps associated with the arithmetic progressions of primes in A005115.at n=13A093364
• Triangle read by rows: T(n,k) is the number of lattice paths from (0,0) to (n,n) using steps E=(1,0), N=(0,1) and D=(1,1) (i.e., bilateral Schroeder paths), having k D=(1,1) steps.at n=48A104684
• Numbers k such that k-1, k+1, 2*k-1, 2*k+1, 3*k-1 and 3*k+1 are primes.at n=2A118859
• A093364 with duplicates removed.at n=9A122763
• Numbers with exactly 6 distinct prime divisors {2,3,5,7,11,13}.at n=13A147573
• Triangle T(n,k) = binomial(2*n-k, k)*binomial(n+k, 2*k), read by rows.at n=48A171822
• Triangle T(n,k) = binomial(2*n-k, k)*binomial(n+k, 2*k), read by rows.at n=51A171822
• Numbers with prime factorization pqrst^2u^2.at n=11A190380
• Average of twin prime pairs n having their decimal expansion of the form abcabc or abcabc0 such that n contains three twin primes as divisors.at n=5A235716
• Number of (n+2) X (3+2) 0..3 arrays with every 3 X 3 subblock row, column, diagonal and antidiagonal sum not equal to 2 3 4 6 or 7.at n=6A252264
• Number of (n+2)X(7+2) 0..3 arrays with every 3X3 subblock row, column, diagonal and antidiagonal sum not equal to 2 3 4 6 or 7.at n=2A252268
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row, column, diagonal and antidiagonal sum not equal to 2 3 4 6 or 7.at n=38A252269
• Triangle of coefficients c(n,i), 1<=i<=n, such that for each n>=2, c(n,i) are setwise coprime; and for all primes p>2n-1, the sum of (-1)^i*c(n,i)*binomial(i*p,p) is divisible by p^(2n-1).at n=29A268512