255840

Appears in sequences

• Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.at n=19A070156
• a(n) = (n+1+(-1)^n)*A024167(n), related to alternating harmonic sums.at n=7A130679
• Draw a regular n-gon and the enclosing circle, then for each pair of vertices X, Y, draw a circle with diameter XY; the union of these figures is the graph H_n; sequence gives number of edges in H_n.at n=31A370979