19674

Appears in sequences

• Number of bipartite partitions.at n=18A002766
• a(n) = n^3 - floor( n/3 ).at n=27A002901
• Theta series of direct sum of 3 copies of hexagonal lattice.at n=27A008654
• a(n) = 3^n - n.at n=9A024024
• a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (composite numbers).at n=43A024588
• s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n-k+1), where k = [ n/2 ], s = (composite numbers).at n=42A025102
• Lengths of successive generations of the Kolakoski sequence A000002.at n=22A054352
• Natural numbers n for which the following three properties hold: (i) Phi[Sigma[n]]=2*phi(n), (ii) Sigma[n-2]=2*Sigma[Phi[n-2]], (iii) Sigma[n+2]=2*Sigma[Phi[n+2]].at n=1A057564
• Number of positive integers <= 10^n that are divisible by no prime exceeding 7.at n=13A106600
• Numbers missing from A109681.at n=8A109682
• Monotonic ordering of nonnegative differences 3^i-9^j, for 40>=i>=0, j>=0.at n=24A192157
• G.f.: exp( Sum_{n>=1} 2*sigma(n*3^n)*x^n/n ).at n=5A193102
• Number of distinct values taken by 5th derivative of x^x^...^x (with n x's and parentheses inserted in all possible ways) at x=1.at n=22A199296
• Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n-2) + 1, where a(0) = 1, a(1) = 3, b(0) = 2, b(1) = 4.at n=17A293316
• Sum of the fifth largest parts in the partitions of n into 7 parts.at n=46A308929
• Numbers k such that k^2 | A038199(k).at n=32A317475
• Total number of composite parts in all partitions of n.at n=33A326981
• a(0) = 1, and for n >= 0, a(n+1) = -A326936(a(n)).at n=12A328653
• Numbers k such that the ring of integers of Q(2^(1/k)) is not Z[2^(1/k)].at n=22A342390