83981

Appears in sequences

• Strong pseudoprimes to base 69.at n=31A020295
• Strong pseudoprimes to base 93.at n=33A020319
• a(n) = (9*6^n+1)/5.at n=6A199412
• Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant in {0,1,...,n}.at n=34A209995
• Expansion of (2 + x + x^2 + x^3 - x^4 - 2*x^5 - 4*x^6 - 8*x^7) / (1 - x^4 + 16*x^8) in powers of x.at n=34A247487
• 11-gonal numbers which are products of two distinct primes.at n=18A354448