222940

Appears in sequences

• Numbers k such that 1*k + 1, 3*k + 1, 9*k + 1, 27*k + 1, 81*k + 1 are all primes.at n=13A112042
• a(0) = 0 by convention; for n>0, a(n) is the number of edges in the n-th figure shown in A255011 (meaning the figure with 4n points on the perimeter).at n=12A331448