23028

Appears in sequences

• Numbers n such that n | Sigma_2(n) + Phi(n)^2.at n=8A055696
• Let r, s, t be three permutations of the set { 1, 2, 3, ..., n }; a(n) = minimal value of Sum_{i=1..n} r(i)*s(i)*t(i).at n=23A070735
• Number of totally ramified extensions over Q_2 with degree n in the algebraic closure of Q_2.at n=11A100979
• Positive numbers of the form x^5-10x^3*y^2+5x*y^4 (where x,y are integers and y>x).at n=17A135792
• Numbers of the form x^5-10x^3*y^2+5x*y^4 (where x,y are integers).at n=23A135793
• Averages of twin prime pairs of A074378.at n=13A154563
• a(n) = 16*n^2 - 2*n.at n=37A158058
• Number of binary strings of length n with no substrings equal to 0001 0011 or 1101.at n=18A164460
• The number of permutations p of {1,...,n} satisfying |p(i)-p(i+1)| is in {4,5} for i from 1 to n-1.at n=36A174708
• Number of 4-step S, NW and NE-moving king's tours on an n X n board summed over all starting positions.at n=30A187378
• Molecular topological indices of the Moebius ladders.at n=18A192833
• Molecular topological indices of the prism graphs Y_n.at n=18A192838
• Number of (w,x,y) with all terms in {0,...,n} and w<x+y and x<=y.at n=37A212982
• Number of compositions of n where the difference between largest and smallest parts equals 2 and adjacent parts are unequal.at n=26A214271
• Let p = n-th prime == 7 mod 8; a(n) = sum of quadratic residues mod p that are < p/2.at n=27A282039
• Averages k of twin primes such that the sum (with multiplicity) of prime factors of k-1, k and k+1 is prime.at n=44A340060
• Ulam numbers sandwiched between twin prime numbers.at n=36A380429