33542145

Appears in sequences

• a(n) = binomial(2^n-1,2).at n=13A134057
• M(M-1)/2, where M is Mersenne prime A000668(n).at n=4A139224
• a(n) = ((2^b-1)/phi(n))*Sum_{d|n} Moebius(n/d)*d^(b-1) for b = 13.at n=1A161024
• Number of holes in a sheet of paper when you fold it n times and cut off the four corners.at n=25A274230
• Three-column array pPT read by rows: subsequence of primitive Pythagorean triples (x, y, z) with x = A153893^2 - A000079^2, y = 2*A153893*A000079, z = A153893^2 + A000079^2, ordered by increasing z.at n=33A334638