19293

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 92.at n=39A031590
• Pair the odd numbers such that the k-th pair is (r, r+2k) where r is the smallest odd number not included earlier: (1, 3), (5, 9), (7, 13), (11, 19), (15, 25), (17, 29), (21, 35), (23, 39), (27, 45), ... This is the sequence of the product of the members of pairs.at n=33A075320
• a(1) = 3; a(n) = smallest number such that the forward as well as the reverse n-th partial concatenation is a prime for n>1. (Reverse concatenation is taken term-wise and not digit-wise).at n=29A083993
• E.g.f. satisfies A(x) = exp( 3*x*A(x) ) / (1-x).at n=4A361182
• Right-truncatable happy numbers: every prefix is a happy number and no digits are zero.at n=26A383638