29013

Appears in sequences

• Number of 2-element intersecting families (with not necessarily distinct sets) whose union is an n-element set.at n=9A053156
• Numbers of form 4^(3*k+l+1)/9 - 4^l/9 - 1/3 or 2*4^(3*k+l+2)/9 - 2*4^l/9 - 1/3, k,l>=0.at n=28A172143
• a(n) is the number of distinct billiard words with length n on an alphabet of 3 symbols.at n=13A180238
• Odd numbers producing exactly 3 odd numbers in the Collatz (3x+1) iteration.at n=17A198584
• Odd numbers having no odd primes in their Collatz (3x+1) trajectory.at n=12A221475
• Odd numbers producing 3 decreasing odd numbers in the Collatz (3x+1) iteration.at n=14A228872
• Numbers with more than one Collatz tripling step whose odd Collatz trajectory does not contain primes.at n=28A319936
• Irregular triangle T read by rows: Row n gives the vertex labels of level n of the tree related to the modified reduced Collatz map A324036.at n=70A324038
• Numbers of the form (2^(2*j + 6*k + 10) - 2^(2*j + 2) - 3)/9, with j,k >= 0.at n=5A342816
• a(1) = 1; a(n) = a(n-1) + 2 * a(floor(n/2)).at n=42A347027
• a(n) = (85*4^n - 1)/3.at n=4A353957