25761

Appears in sequences

• Fermat pseudoprimes to base 2, also called Sarrus numbers or Poulet numbers.at n=38A001567
• Euler pseudoprimes: composite numbers n such that 2^((n-1)/2) == +-1 (mod n).at n=21A006970
• Composite numbers k such that k == +-1 (mod 8) and 2^((k-1)/2) == 1 (mod k).at n=16A006971
• StirlingS2[ n,m ] triangle summed down the columns.at n=50A036560
• Row sums of convolution triangle A030527.at n=4A046088
• Euler-Jacobi pseudoprimes: 2^((n-1)/2) == (2 / n) mod n, where (2 / n) is a Jacobi symbol.at n=17A047713
• Pseudoprimes k to base 2 such that k-2 and k+2 are primes.at n=1A057942
• Sarrus numbers n (A001567) which satisfy mu(n) = -1 and which are not Super-Poulet numbers (A050217).at n=17A074380
• Sarrus numbers with more than 2 distinct prime factors.at n=20A080747
• Pseudotwinprimes p+2 for primes p such that p+2 divides p^(p+2)+2 and p+2 is composite.at n=12A100873
• Number of Motzkin paths of length n having no consecutive (1,0) steps.at n=14A104545
• Octagonal numbers for which the sum of the digits is also an octagonal number.at n=11A117082
• 3-almost prime octagonal numbers.at n=20A129927
• Octagonal numbers which are the sums of exactly two positive octagonal numbers.at n=17A136346
• Sarrus numbers that become prime when two is added.at n=6A137198
• Triangle read by rows, A000012 * A008277.at n=50A137649
• Odd composite numbers k for which k = A140607((k-1)/2).at n=4A140667
• Row sums of triangle A141155.at n=18A141156
• Sarrus numbers A001567 that are not Carmichael numbers A002997.at n=29A153508
• G.f.: A(x) = exp( Sum_{n>=1} 3*A038500(n) * x^n/n ), where A038500 is the highest power of 3 dividing n.at n=36A161809