21647

Properties

Appears in sequences

• Primes or negative values of primes in the sequence b(n) = 47*n^2 - 1701*n + 10181, n >= 0.at n=42A050267
• Primes such that prime(p) +- pi(p) are simultaneously prime.at n=35A065117
• Lesser of twin balanced primes (A090403).at n=10A096694
• Balanced primes of order nine.at n=14A096701
• Number of n-bit strings that contain no more than 4 zeros and no more than 2 leading and 2 trailing zeros.at n=14A102026
• Larger of two consecutive primes whose sum is a square.at n=15A118591
• Numbers k such that (8^k + 5^k)/13 is prime.at n=6A128338
• Numerators of the continued fraction convergents of the decimal concatenation of the even natural numbers.at n=9A128842
• Primes of the form 47*n^2 - 1701*n + 10181.at n=21A128878
• Primes of the form (4k^2 + 4k - 5)/5.at n=19A154619
• Lesser member p of a twin prime pair (p, p + 2) such that 2p + 3(p + 2) is a perfect square.at n=5A174370
• Hilltop maps: number of n X 1 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..2 n X 1 array.at n=14A218199
• The first member of a twin prime pair whose sum equals the sums of k consecutive smaller pairs of twin primes, k=3.at n=23A226692
• Primes of the form 43*n^2 - 537*n + 2971 in order of increasing nonnegative values of n.at n=28A272285
• Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n-1) + 1, where a(0) = 1, a(1) = 2, b(0) = 3, and (a(n)) and (b(n)) are increasing complementary sequences.at n=17A294542
• Primes p such that the base-10 concatenations (p+1)||p and (p+1)||(p+1)||p are both prime.at n=42A309749
• Primes p such that p+2, (p+1)||p and (p+1)||(p+2) are primes (where || denotes concatenation in base 10).at n=27A309934
• Number of divisors d of A076954(n) with distinct prime multiplicities such that the numerator of A006939(n)/d also has distinct prime multiplicities.at n=9A336871
• Lesser of twin primes p such that p and p+2 are both in A115591.at n=19A367318
• Prime numbersat n=2430