18330

Appears in sequences

• Numbers k such that sigma(k) = sigma(k+6).at n=37A015866
• Number of nonisomorphic commutative groupoids with 1 idempotent and no symmetry.at n=3A030264
• Triangle: T(n,k), k<=n: commutative groupoids with no symmetry with n elements and k idempotents.at n=11A038022
• Numbers whose sum of the squares of divisors is also a square number.at n=12A046655
• Mean divisor of n differs by <= 1 from mean divisor of all numbers from 1 to n-1.at n=22A049010
• Numbers n such that x^n + x^11 + 1 is irreducible over GF(2).at n=32A057481
• Numbers k such that the sum of unitary divisors of k^2 is a square.at n=12A064498
• a(n) is the number of terms in the expansion of (x+y+z)*(x^2+y^2+z^2)*(x^3+y^3+z^3)*...*(x^n+y^n+z^n).at n=18A086796
• Numbers n that raised to the powers from 1 to k (with k>=1) are multiple of the sum of their digits (n raised to k+1 must not be a multiple). Case k=9.at n=22A135194
• (n^4 - 10*n^2 + 15*n - 6)/2.at n=13A135916
• Row sums of triangle defined in A095181.at n=19A160915
• Number of nX7 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=3A207948
• T(n,k)=Number of nXk 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=48A207949
• Number of 4 X n 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=6A207950
• Antidiagonal sums of the convolution array A213822.at n=11A213824
• Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.at n=4A251021
• Number of (n+1)X(5+1) 0..3 arrays with no 2X2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.at n=0A251025
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with no 2X2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.at n=10A251028
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with no 2X2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.at n=14A251028
• a(n) = ( 2*n*(2*n^2 + 11*n + 26) - (-1)^n + 1 )/16.at n=40A256666