69001

Properties

Appears in sequences

• Numbers whose least quadratic nonresidue (A020649) is 19.at n=31A025027
• Primes which become emirps when rotated by 180 degrees on a digital clock display.at n=19A145750
• Primes of the form 1000*k + 1.at n=14A156655
• a(n) = (16/3)*(n+1)*n*(n-1) + 8*n^2 + 1.at n=22A212668
• Primes which become squares when the digits are rotated once to the right.at n=31A234925
• Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + … + d_(2)*10 + d_(1). Sequence lists the numbers n such that sigma(n) - n = Sum_{i=1..k-1}{sigma(Sum_{j=1..i}{d_(j)*10^(j-1)}) - Sum_{j=1..i}{d_(j)*10^(j-1)}} (see example below).at n=42A240894
• Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + ... + d_(2)*10 + d_(1). Sequence lists the numbers n such that n' = Sum_{i=1..k-1}{Sum_{j=1..i}{d_(j)*10^(j-1)}}', where n' is the arithmetic derivative of n (see example below).at n=43A244078
• Invertible primes p such that k*p - 1 and k*p + 1 is a twin prime pair; for k = 12.at n=8A317029
• a(0) = 1; for n > 0, a(n) is the coefficient of x^a(n-1) in the expansion of Product_{k=0..n-1} (x^a(k) + 1 + 1/x^a(k)).at n=21A367736
• Prime numbersat n=6855