21944

Appears in sequences

• Dirichlet convolution of Fibonacci numbers with themselves.at n=20A034744
• First gap of n in sequence A038593 (upper terms).at n=12A038662
• Number of nonisomorphic self-complementary circulant digraphs (Cayley digraphs for the cyclic group) of order 2n-1.at n=19A049309
• Sums of squares of primitive roots of primes.at n=16A089453
• Numbers k such that both k and k+1 are abundant.at n=5A096399
• Numbers k such that both sigma(k) >= 2*k-1 and sigma(k+1) >= 2*(k+1)-1.at n=7A103289
• Poincaré series [or Poincare series] P(C_{3,2}(0); t).at n=31A124636
• a(n) = n^3 - 8.at n=28A259348
• Positions of squares in A276573.at n=50A277014
• a(n), n>1, is the smallest number k whose symmetric representation of sigma(k) has two parts and has a larger number of legs in its two parts than a(n-1); a(1)=3.at n=29A279105
• G.f. A(x) satisfies: A(x - x*A(x)) = x + 3*x*A(x).at n=5A291819
• Cogrowth sequence for the Heisenberg group.at n=5A307468
• Numbers k such that both k and k+1 are bi-unitary abundant numbers.at n=1A318167
• Numbers k such that both k and k+1 are infinitary abundant numbers (A129656).at n=1A327635
• Numbers k such that both k and k+1 are Zumkeller numbers (A083207).at n=3A328327
• Number of balanced reduced multisystems of weight n and maximum depth whose atoms cover an initial interval of positive integers.at n=6A330676
• Let t_k denote the triangular number k*(k+1)/2. Suppose 0 < x < y < z are integers satisfying t_x + t_y = t_p, t_y + t_z = t_q, t_x + t_z = t_r, for integers p,q,r. Sort the triples [x,y,z] first by x, then by y. Sequence gives the values of z.at n=47A332590
• Even composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 7 (mod m), where U(m)=A004187(m) and V(m)=A056854(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=7 and b=1, respectively.at n=36A337782
• Even composite integers m such that A004254(m)^2 == 1 (mod m).at n=34A338314
• a(n) = Sum_{k=1..n} floor(n/k) * 4^(k-1).at n=7A344815