20161

Properties

Appears in sequences

• Numbers k such that (11^k - 1)/10 is prime.at n=10A005808
• Primes that divide at least one term of Sylvester's sequence s = A000058: s(n+1) = s(n)^2 - s(n) + 1, s(0) = 2.at n=32A007996
• Primes of form k^2 - 3.at n=26A028874
• Number of partitions satisfying (cn(0,5) <= cn(1,5) = cn(4,5)).at n=53A036809
• Base-5 digits are, in order, the first n terms of the periodic sequence with initial period 1,1,2.at n=6A037530
• Primes p such that p-12, p and p+12 are consecutive primes.at n=18A053072
• Prime number spiral (clockwise, East spoke).at n=24A054555
• Primes p for which the period of reciprocal 1/p is (p-1)/12.at n=24A056217
• Luhn primes: primes p such that p + (p reversed) is also a prime.at n=32A061783
• Primes of the form 4*k! + 1.at n=2A062538
• Cyclotomic polynomials Phi_n at x=phi, divided by sqrt(5) and rounded to nearest integer (where phi = tau = (sqrt(5)+1)/2).at n=35A063706
• Cyclotomic polynomials Phi_n at x=phi divided by sqrt(5) and ceiled up (where phi = tau = (sqrt(5)+1)/2).at n=35A063708
• Primes p such that p-1 is a highly composite number.at n=12A072826
• Trajectory of n under the Reverse and Add! operation carried out in base 3 (presumably) does not reach a palindrome and (presumably) does not join the trajectory of any term m < n.at n=47A077405
• Numbers k such that k, sigma(k) and phi(k) have the same decimal digits (ignoring multiplicity).at n=24A082059
• Smallest prime that is the product of n consecutive integers + 1, or 0 if no such number exists.at n=5A083521
• Smallest prime obtained as a product of n terms of an arithmetic progression + the common difference.at n=5A088120
• Primes of the form (k! + 2)/2.at n=4A089130
• Primes in the progression (n! + m)/m where n advances by 1 and m resets to 1 upon each prime occurrence.at n=7A089136
• Primes p such that tau(p-1)+tau(p+1) is larger than for any previous term. (Smallest prime sandwiched between more composite numbers.)at n=27A090481