21424

Appears in sequences

• a(n) = n^5 - (n-1)^5 + (n-2)^5 - ... +(-1)^n*0^5.at n=8A062393
• a(n) = A051201(2^n).at n=12A078161
• Numbers n such that 2*n*k(n) is rational but not an integer, where k(n) is sum of successive remainders when computing the Euclidean algorithm for (1, 1/sqrt(n)) as defined in A086378 (MuPAD program is given there); numbers belonging to A086378 but not to A088900.at n=14A087414
• Numbers n such that n^24 + 1 = p*q with p,q distinct primes.at n=35A119982
• Number of partitions of n such that (number parts having multiplicity 1) is not a part and (number of parts > 1) is not a part.at n=44A241514
• Number of compositions (ordered partitions) of n into multiplicatively perfect numbers (A007422).at n=34A282569
• Number of n X 2 0..1 arrays with no 1 equal to more than one of its king-move neighbors, with the exception of exactly one element.at n=9A282785
• Numbers k such that e(k) > 1 and k == e(k) (mod lambda(k)), where e(k) = A051903(k) is the maximal exponent in prime factorization of k.at n=18A327295
• a(n) is the Pisano period of prime(n)^2.at n=26A343116
• On a diagonally numbered square grid, with labels starting at 1, this is the number of steps that a (1,n) leaper makes before getting trapped when moving to the lowest available unvisited square, or -1 if it never gets trapped.at n=31A352730
• Numbers k such that k and k+1 have the same sum of 5-smooth divisors.at n=13A355713
• a(n) = prime(n)*(prime(n-1) + prime(n+1)).at n=25A357679
• Long legs of the only primitive Pythagorean triple whose inradius is the n-th prime and whose short leg is an odd number.at n=26A367573
• Numbers k such that sigma(k) = psi(k) + phi(k) + tau(k)^2.at n=14A390421