21967

Appears in sequences

• Least positive number k such that 2^k mod k = 2n+1, or 0 if no such k exists.at n=25A124977
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 1), (-1, 1, 0), (1, -1, 0), (1, 1, 0)}.at n=9A149146
• G.f.: Product_{n>=1} (1 + x^n + x^(n+1)).at n=39A160571
• a(n) = A066186(n) - A004125(n).at n=21A162362
• a(n) is the smallest term m in A173978 for which A020639(2m-3) = prime(n), n > 1.at n=43A173980
• Numbers k such that k divides the sum of digits in factorial base of all numbers from 1 to k.at n=22A333702
• Records in A360519.at n=37A361107