21541

Appears in sequences

• Number of partitions satisfying (cn(2,5) = cn(3,5) and cn(0,5) <= cn(1,5) and cn(0,5) <= cn(4,5)).at n=51A036805
• a(1) = 3; a(n) = smallest number such that the forward as well as the reverse n-th partial concatenation is a prime for n>1. (Reverse concatenation is taken term-wise and not digit-wise).at n=37A083993
• Numbers whose sum of divisors equals the sum of their anti-divisors.at n=11A178029
• Numbers whose sum of their anti-divisors divides the sum of their divisors.at n=16A191581
• Number of partitions of n+5 with largest inscribed rectangle having area <= n.at n=32A218626
• Numbers n such that the sum of the distinct prime factors of prime(n)-1 and prime(n+1)-1 are the same.at n=16A259562
• Numbers whose sum of anti-divisors is equal to the sum of its unitary divisors.at n=16A273992