308481

Appears in sequences

• a(n) = (1/3)*(n^2 + 2*n + 3)*(n+1)^2.at n=30A014820
• Octagonal numbers equal to S*(3S - 2) with 3S - 2 = k^2 and S semiprime.at n=12A124106
• Octagonal numbers of the form C*(3C - 2) with 3C - 2 = k^2 and C a composite number.at n=14A125511
• Crystal ball sequence for the lattice C_4.at n=15A142993
• Odd numbers n divisible by 3 such that for all k >= 1 the numbers n*2^k + 1 and n*2^(k+1) + 1 do not form a pair of primes.at n=21A243857
• Odd numbers n not congruent to 5 mod 6 such that for all k >= 1 the numbers n*4^k + 1 are composite.at n=2A251057
• Odd numbers n divisible by 3 such that for all k >= 1 the numbers n*4^k + 1 are composite.at n=1A256002