57421

Appears in sequences

• Strong pseudoprimes to base 69.at n=27A020295
• Strong pseudoprimes to base 79.at n=30A020305
• Number of ordered rooted trees with n non-root nodes and all outdegrees <= six.at n=11A036768
• Sarrus numbers n (A001567) which satisfy mu(n) = -1 and which are not Super-Poulet numbers (A050217).at n=26A074380
• Sarrus numbers with more than 2 distinct prime factors.at n=32A080747
• A sequence generated from a 4th degree Pascal's Triangle polynomial.at n=20A095265
• Number of sum of squares representations of n^2 in n dimensions disregarding order and sign.at n=20A105152
• Least positive k such that 10^n + {k, k+2, k+6, k+8} are all prime.at n=10A121066
• Number of binary strings of length n with no substrings equal to 000, 010, or 111.at n=50A164317
• Fermat pseudoprimes to base 2 of the form (6*k + 1)*(6*k*n + 1), where k, n are integers different from 0.at n=30A214607
• Fermat pseudoprimes to base 2 with three prime factors.at n=26A215672
• Composite integers k such that 2^k == 2 (mod k*(k+1)).at n=17A217465
• Number of 2 X n 0..3 arrays with antidiagonals unimodal and rows and diagonals nondecreasing.at n=10A223962
• Fermat pseudoprimes to base 2 which are not Euler pseudoprimes to base 2.at n=24A227136
• Number of compositions of 2n such that the largest multiplicity of parts equals n.at n=11A232665
• Number of length 5+2 0..n arrays with every three consecutive terms having the sum of some two elements equal to twice the third.at n=39A248438
• Poulet numbers which are not super-Poulet numbers.at n=32A306487
• a(n) = Sum_{k=0..floor(n/2)} binomial(n+k-1,k) * binomial(k,n-2*k).at n=12A389289