18180

Appears in sequences

• Number of nonnegative solutions of x1^2 + x2^2 + ... + x9^2 = n.at n=28A045851
• Conjectured largest number that is not the sum of three generalized n-gonal numbers, or -1 if there is no largest number.at n=8A118282
• Conjectured largest number that is not the sum of three generalized (2n+1)-gonal numbers; bisection of A118282.at n=4A118284
• Diagonal sums of number triangle A123490.at n=11A123491
• Number of n X n arrays of squares of integers summing to 28.at n=1A159421
• Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 2.at n=21A245142
• Numbers k with the property that p = k^2 - 11 and q = k^2 + 11 are consecutive primes.at n=27A248790
• Number of (n+2)X(2+2) 0..3 arrays with every consecutive three elements in every row, column, diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=6A253038
• Number of (n+2)X(7+2) 0..3 arrays with every consecutive three elements in every row, column, diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=1A253043
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every consecutive three elements in every row, column, diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=29A253044
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every consecutive three elements in every row, column, diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=34A253044
• Numbers n such that the sum of the digits of the numbers from 1 to n divides the sum of the numbers from 1 to n.at n=22A272360
• Square array T(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of g.f. 1/(1 - 2*k*x + k*x^2).at n=59A342133
• Smaller member of a nonexponential amicable pair: numbers (k, m) such that nesigma(k) = m and nesigma(m) = k, where nesigma(k) is the sum of the nonexponential divisors of k (A160135).at n=1A348602
• Triangle read by rows: T(n,k) is the number of digraphs on n labeled nodes with k arcs and a global source and sink, n >= 1, k = 0..max(1,n-1)*(n-2)+1.at n=23A350791
• Irregular triangle read by rows. T(n,k) is the number of properly colored simple labeled graphs on [n] with exactly k edges, n >= 0, 0 <= k <= binomial(n,2).at n=17A361456
• Numbers that are a sum of both four and six consecutive prime numbers.at n=30A380433
• Numbers k such that the total number of digits d in the numbers from 1 to k is even for each d from 0 to 9.at n=37A380642
• Triangle Read by rows: T(n,k) is the number of rooted ordered trees with n non-root nodes with non-root node labels in {1,..,k} such that all labels appear at least once in all groups of sibling nodes.at n=39A385123
• A005117(k) - 1 where k is the least k such that A389412(k) = n.at n=42A389879