21347

Properties

Appears in sequences

• prime(k) for those k where floor((2*(prime(k+1)-prime(k))*PrimePi(k) mod (8*k))/k) = m with m = 8.at n=39A109562
• Primes p such that q-p = 30, where q is the next prime after p.at n=24A124596
• Right truncatable primes in base 9 (written in decimal form).at n=44A129693
• Cumulative concatenation of A000032 Lucas numbers (beginning at 2).at n=4A131698
• Primes congruent to 58 mod 61.at n=35A142856
• Primes of the form (1 + k + k^3)/3.at n=5A163512
• Primes p=prime(i) of level (1,4), i.e., such that A118534(i) = prime(i-4).at n=7A216177
• Lesser of consecutive primes whose sum is a palindromic number.at n=26A242386
• Prime time primes on 6-digit clocks, second definition: primes of the form HMMSS where H, MM, SS are primes, H < 24, MM and SS < 60.at n=31A295013
• Prime numbers which satisfy the regex m1{1,m1}m2{1,m2}m3{1,m3}m4{1,m4}m5{1,m5} where mi are one-digit Lucas numbers.at n=0A319017
• Number of unlabeled rooted trees with n nodes in which the non-leaf branches directly under any given node are all equal.at n=15A320222
• a(n) = Sum_{k=1..n} k * floor(n/k)^3.at n=23A350108
• Discriminants of imaginary quadratic fields with class number 33 (negated).at n=32A351671
• Primes p_1 where products m of k = 5 consecutive primes p_1..p_k are such that only p_1 < m^(1/k).at n=25A376136
• Prime numbersat n=2397