70544

Appears in sequences

• Number of equilateral triangles formed out of matches that can be found in a hexagonal chunk of side length n in hexagonal array of matchsticks.at n=27A045949
• Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and first and second differences in -1..1.at n=27A208963
• Numerator of Sum_{k=0..n} (2^k * (k!)^2)/(2k + 1)!.at n=6A277586
• a(0) = 1; a(n) = Sum_{k=1..n} -lambda(k+1)*a(n-k), where lambda() is the Liouville function (A008836).at n=29A307240
• a(n) is the determinant of the 2 X 2 matrix whose entries (when read by rows) are the n-th primes congruent to 1, 3, 5, 7 mod 8 respectively.at n=22A337145