21893

Properties

Appears in sequences

• a(n) = a(n-1) + a(n-2) - 1.at n=21A001588
• Number of bipartite partitions of n white objects and 8 black ones.at n=10A002757
• Number of bipartite partitions of n white objects and 10 black ones.at n=8A002759
• Coordination sequence for sigma-CrFe, Position Xa.at n=37A009962
• Primes p such that p, p+18, p+36 are consecutive primes.at n=1A052189
• Fifth term of weak prime sextet: p(m-3)-p(m-4) < p(m-2)-p(m-3) < p(m-1)-p(m-2) < p(m)-p(m-1) < p(m+1)-p(m).at n=8A054832
• Operation count to create all permutations of n distinct elements using Algorithm L (lexicographic permutation generation) from Knuth's The Art of Computer Programming, Vol. 4, chapter 7.2.1.2. Sequence gives number of interchange operations in step L4.at n=6A080049
• a(n) is the smallest prime == 1 (mod F(n)) where F(n) is the n-th Fibonacci number.at n=20A087384
• Primes of the form n^2 - 11.at n=19A091272
• n_F(n) where F() = Fibonacci numbers A000045.at n=20A122629
• Primes of the form 2*F(k) + 1.at n=9A124081
• Smallest prime of the form k*prime(n+1)+prime(n) = j*prime(n+2)+prime(n+1) for free integer multipliers k and j.at n=33A129918
• K-bit primes p such that p-2^i and p+2^i are composite for 0<=i<=K-1.at n=13A153352
• Larger of 3 consecutive prime numbers such that p1*p2*p3*d1*d2=average of twin prime pairs; p1,p2,p3 consecutive prime numbers; d1(delta)=p2-p1, d2(delta)=p3-p2.at n=19A153411
• Primes of form 5+38*n^2.at n=18A173554
• Primes that are the sum of squares of three positive Fibonacci numbers.at n=32A191375
• Smallest possible largest element of a 3 by n average array where repetitions are allowed with no diagonals.at n=12A195747
• Triangle read by rows: T(n,k) (0 <= k <= n) is the number of partitions of (n,k) into a sum of pairs.at n=63A201376
• Odd numbers m that are neither of the form p + 2^k nor of the form p - 2^k with 2^k < m, k >= 1, and p prime.at n=29A255967
• Primes which are not the sums of two consecutive non-Fibonacci numbers.at n=15A257110