20183

Properties

Appears in sequences

• a(0) = 1, a(n) = 21*n^2 + 2 for n>0.at n=31A010011
• a(n) is the smallest prime p such that p, p+d, and p+2d are consecutive primes where d = 2 for n = 1 and d = 6*(n-1) for n > 1.at n=3A052187
• Primes p such that p, p+18, p+36 are consecutive primes.at n=0A052189
• Least prime in A031936 (lesser of 18-twins) whose distance to the next 18-twin is 2*n.at n=0A052358
• The smallest initial prime of 2 non-overlapping d-twin primes if the distance between pairs (D) is minimal (see A052380).at n=8A052381
• Sum of the second moments of all partitions of n with weights starting from 0.at n=15A066188
• Safe primes (A005385) (p and (p-1)/2 are primes) such that 12*p+1 is also prime.at n=46A075707
• Primes of the form 6n^2 - 1.at n=22A090686
• Primes p = p_(n+1) such that p_n + p_(n+2) = 2*p_(n+1) + 12.at n=18A095673
• Number of partitions of n having positive even rank (the rank of a partition is the largest part minus the number of parts).at n=45A101708
• Primes congruent to 53 mod 61.at n=38A142851
• Primes congruent to 35 mod 73.at n=30A154628
• a(n) = 841*n - 1.at n=23A158402
• a(n) = 24*n^2 - 1.at n=28A158544
• Numerators in Taylor series expansion of Product_{n >= 1} (1+x^n/n!).at n=12A170908
• Primes of the form 7*x^2 - 5*y^2, where x and y are successive natural numbers.at n=36A176557
• Number of nondecreasing arrangements of n+2 numbers in 0..n with the last equal to n and each after the second equal to the sum of one or two of the preceding three.at n=36A190034
• First of three consecutive primes in arithmetic progression with gap of 6n, and such that a(n) > a(n-1).at n=2A224325
• Primes p such that 10*p-1, 10*p-3, 10*p-7 and 10*p-9 are all prime.at n=12A243408
• a(1)=3; for n>1, if n is odd a(n) = spf(Product_{k=1..n-1}(a(k))+1) else a(n) = spf(Product_{k=1..n-1}(a(k))-1), where spf is "smallest prime factor".at n=41A265009