21017

Properties

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 59.at n=31A020398
• Primes of the form k^2 - 8.at n=33A028886
• Triangle of numbers arising in recursive computation of A002212.at n=43A073149
• Primes of the form x^2 + (x+3)^2.at n=23A076727
• Median term of prime 5-tuples (p, p+2, p+6, p+8, p+12).at n=6A090286
• a(n) is the smallest lesser of twin prime p, such that prime(2 + p) - prime(p) = 2n (cf. A096474).at n=36A096475
• Primes occurring in exactly three prime triples (p,q,r) with p<q<r=p+6.at n=14A098423
• Prime quadruples: 3rd term.at n=19A136721
• Primes A080478(n)^2 + A080478(n+1)^2.at n=16A139361
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 0), (-1, 1, 0), (0, 1, 1), (1, 0, -1)}.at n=10A148442
• a(1) = 1; thereafter a(n) is always the smallest integer > a(n-1) not leading to a contradiction, such that any five consecutive digits in the sequence sum up to a prime.at n=31A152605
• Depression-type primes with five digits; from left to right digits decrease to and increase from the central digit.at n=1A157083
• Initial members of prime triples (p, p+2, p+6) for which also the sum 3p+8 is prime.at n=26A162001
• Smallest prime p such that n primes exist between the prime triple (p, p+2, p+6) and the next prime triple.at n=26A214450
• Prime intersections in a square spiral with positive integers: primes p such that there are four primes among eight nearest neighbors of p.at n=8A215470
• Number of 5 X n 0..1 arrays with diagonals and antidiagonals unimodal and rows nondecreasing.at n=9A223952
• Primes of the form p(k)^2 + q(m)^2 with k > 0 and m > 0, where p(.) is the partition function (A000041), and q(.) is the strict partition function (A000009).at n=55A233346
• Primes p such that p - 2^2, p - 4^2 and p - 6^2 are all positive primes.at n=29A246873
• Non-palindromic balanced primes in base 2.at n=41A256081
• Table read by rows: list of prime 5-tuples of the form (p, p+2, p+6, p+8, p+12).at n=32A270998