18060

Appears in sequences

• Perimeters of more than one primitive Pythagorean triangle.at n=31A024408
• a(n) = dot_product(1,2,...,n)*(7,8,...,n,1,2,3,4,5,6).at n=33A026049
• Smallest multiple of n with a prime signature different from all previous terms.at n=42A069875
• Numbers k such that k-1, k+1 and k^2+1 are prime numbers.at n=33A070155
• Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.at n=4A070156
• Numbers k such that the sign of core(k)-phi(k) is not equal to 2*mu(k)^2-1, where core(k) is the squarefree part of k.at n=31A070237
• Numbers k such that k+1, k^2+1 and k^4+1 are primes.at n=39A070325
• a(n) = 3 + floor((2 + Sum_{j=1..n-1} a(j))/3).at n=30A120150
• Sum of all n-digit highly composite numbers.at n=3A127390
• Numbers m such that m^4-1 has no divisors d with 1 < d < m-1.at n=34A129293
• 6 times heptagonal numbers: a(n) = 3*n*(5*n-3).at n=35A153786
• Number of 11 X 11 arrays of squares of integers, symmetric about the diagonal and under 90-degree rotation, with all rows summing to n.at n=48A156407
• a(n) = 10*n*(n+1).at n=42A163761
• a(n) = n*(2*n^2 + 5*n + 3).at n=20A163815
• Triangle T(n, k, q) = Sum_{j=0..10} q^j * floor( binomial(n+1,k)*binomial(n-1,k-1)/(2^j*(n+1)) ) for q = 2, read by rows.at n=40A174044
• Numbers with prime factorization pqrst^2.at n=31A189983
• Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,1,0,2,3 for x=0,1,2,3,4.at n=3A196944
• Number of nX4 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 4,1,0,2,3 for x=0,1,2,3,4.at n=3A196946
• T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,1,0,2,3 for x=0,1,2,3,4.at n=24A196950
• Triangle of coefficients of polynomials u(n,x) jointly generated with A209136; see the Formula section.at n=51A209135