18215

Appears in sequences

• Expansion of (1-x)^2/(1-3*x+x^3).at n=10A052545
• Numbers k such that A055079(k) = 2^k.at n=39A057838
• Numbers m such that sigma(m+1)+sigma(m-1) = 6*phi(m).at n=14A067243
• Numbers k such that phi(k) divides (sigma(k+1) + sigma(k-1)).at n=44A067244
• a(n) = index of triangular number A077002(n).at n=12A077003
• Matrix log of triangle A117396.at n=47A117398
• a(n) = prime(n)*prime(n+1) + prime(n) + prime(n+1).at n=31A126199
• a(n) = 729*n^2 - 2*n.at n=4A158394
• Number of 12-core partitions of n.at n=56A192061
• Number of 8X2 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 8 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=14A192708
• Number of partitions of n such that the number of parts having multiplicity >1 is a part and the number of distinct parts is not a part.at n=41A241411
• Number of compositions of n whose standard factorization into Lyndon words has distinct strict compositions as factors.at n=20A299024
• G.f.: Sum_{n>=0} (n+1)*(n+2)*(n+3)/3! * x^n * (1 + x^n)^n.at n=28A326004