91001

Appears in sequences

• G.f.: (1 + x^3 + x^4 + ... + x^12 + x^15)/Product_{i=1..10} (1 - x^i).at n=41A003403
• Strong pseudoprimes to base 55.at n=25A020281
• Strong pseudoprimes to base 72.at n=34A020298
• Strong pseudoprimes to base 98.at n=38A020324
• Sarrus numbers n (A001567) which satisfy mu(n) = -1 and which are not Super-Poulet numbers (A050217).at n=32A074380
• Pseudoquadprimes: p+4 for primes p where p+4 divides p^(p+4) + 4 and p+4 is composite.at n=14A100875
• Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1000-1000-1100-0111 pattern in any orientation.at n=17A147105
• Numbers m such that exactly half of the a such that 0<a<m and (a,m)=1 satisfy a^(m-1) == 1 (mod m).at n=20A191311
• Numbers in A191311 but not in A129521.at n=8A191592
• Fermat pseudoprimes to base 2 with three prime factors.at n=32A215672
• Fermat pseudoprimes to base 2 which are not Euler pseudoprimes to base 2.at n=32A227136
• Numbers k such that 2^(k-1) == 1 (mod k) and lpf(k)-1 does not divide k-1.at n=7A316906
• "Strong impostors" not divisible by 4: Those numbers s !== 0 (mod 4) such that lambda(s) | 2(s-1), where lambda is the Carmichael function (A002322).at n=49A318555
• Composite numbers k of the form 4u+1 for which the odd part of phi(k) divides k-1.at n=35A339870