18426

Appears in sequences

• Number of positive integers <= 2^n of form x^2 + 2 y^2.at n=16A000067
• a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = A000201 (lower Wythoff sequence).at n=42A024685
• Number of n-celled polyplets without bilateral symmetry.at n=7A030235
• "CFK" (necklace, size, unlabeled) transform of 2,2,2,2...at n=21A032139
• Start with a single triangle; at n-th generation add a triangle at each vertex, allowing triangles to overlap; sequence gives number of triangles in n-th generation.at n=23A061776
• Pentagonal numbers not divisible by 10 whose reverse is triangular.at n=4A066757
• a(0)=0; a(n) = n^2*a(n-1) + 1.at n=5A066998
• Number of isomorphism classes of associative non-commutative closed binary operations on a set of order n, listed by class size.at n=61A079200
• Number of isomorphism classes of associative non-commutative non-anti-associative non-anti-commutative closed binary operations on a set of order n, listed by class size.at n=61A079207
• a(n) = 9*2^n - 6.at n=11A089143
• Expansion of g.f. x*(x-1)*(x+1)^3/((2*x^3+x^2-1)*(x^4+1)).at n=26A107853
• Pentagonal numbers that are the sum of a nonzero pentagonal number and a nonzero square in at least one way.at n=40A134938
• Number of permutations in S_n avoiding 25{bar 1}34 (i.e., every occurrence of 2534 is contained in an occurrence of a 25134).at n=8A137538
• a(n) is the smallest positive number B that yields a solution for k = A167219(n).at n=34A167221
• Fourth powers (n * n * n * n) in carryless arithmetic mod 10.at n=12A169886
• Fourth powers (n * n * n * n) in carryless arithmetic mod 10.at n=36A169886
• Number of 9X2 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 9 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=13A192709
• a(n) = 3*n*(9*n - 1)/2.at n=37A268351
• Expansion of 1/(1 - Sum_{k>=1} lambda(k)*x^k), where lambda() is the Liouville function (A008836).at n=34A307076
• Sum of the sixth largest parts of the partitions of n into 10 parts.at n=44A326593