81050

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 18.at n=30A031606
• Numbers k such that k-1, k-3, k-7 and k-9 are all prime.at n=33A064974
• a(n) is the total number of elements in all sum-free subsets of {1,...,n}.at n=20A288888
• Numbers m such that 72*m + 1, 576*m + 1, 648*m + 1, 1296*m + 1, and 2592*m + 1 are all primes.at n=19A372187