20786

Appears in sequences

• Number of indecomposable self-dual binary codes of length 2n.at n=17A003178
• Convolution of odd numbers and primes.at n=26A023662
• Numbers k that, when expressed in base 4 and then interpreted in base 9, give a multiple of k.at n=21A062925
• Numbers k such that 2*10^k + 7*R_k - 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=9A098960
• Number of indecomposable Type I but not Type II binary self-dual codes of length 2n.at n=17A106164
• a(n) is the number of binary strings of length n such that there exist 4 or more ones in a subsequence of length 5 or less.at n=14A130902
• Maximal length of rook tour on an n X n+1 board.at n=30A152132
• Maximal length of rook tour on an n X n+3 board.at n=29A152134
• For a lesser p=A001359(n-1), n>=2, of twin primes, let B_k be the sequence defined as A159559 but with initial term k; a(n) is the smallest m such that B_(p+2)(m)-B_p(m) = max_{t>=2} (B_(p+2)(t)-B_p(t)).at n=47A276831
• Number of dissections of an n-gon by nonintersecting diagonals into polygons with a prime number of sides counted up to rotations.at n=10A295495
• Number of balanced reduced multisystems whose atoms cover an initial interval of positive integers with multiplicities equal to the prime indices of n.at n=44A318846
• Even composite integers m such that A004254(m)^2 == 1 (mod m).at n=33A338314