151643

Properties

Appears in sequences

• Let r_1 = 1. Let r_{m+1} = r_1 + 1/(r_2 + 1/(r_3 +...(r_{m-1} + 1/r_m)...)), a continued fraction of rational terms. Then a(n) is the sum of the (positive integer) terms in the simple continued fraction of r_n.at n=16A138744
• a(n) is the least integer k such that 1/(Sum_{j=1..n} 1/phi(k*j)) is an integer.at n=33A341810
• Primes that are the concatenation p|q of two primes p and q with the same number of digits, where r = (p+q)/2, r|q and p|r are all primes.at n=9A358420
• Prime numbersat n=13993