20477

Properties

Appears in sequences

• Sum of squares of the first n primes.at n=17A024450
• Primes at which the difference pattern X24Y (X and Y >= 6) occurs in A001223.at n=37A052163
• a(n) = p is the smallest prime such that p = n + h(n)^2 and p is the first prime following h(n)^2. The smallest immediate post-square primes with distance n = p - h(n)^2.at n=27A058056
• Consider the line segment in R^n from the origin to the point v=(2,3,5,7,11,...) with prime coordinates; let d = squared distance to this line from the closest point of Z^n (excluding the endpoints). Sequence gives d times v.v.at n=17A059804
• a(n) = 2*p + 2*n - 1, where p is the least prime such that next_prime(2*p) - 2*p = 2*n - 1.at n=15A059847
• Luhn primes: primes p such that p + (p reversed) is also a prime.at n=40A061783
• Let u(1)=u(2)=1, u(3)=n, u(k) = (1/2)*abs(2*u(k-1) -u(k-2)-u(k-3)); sequence gives values of n such that Sum_{k>=1} u(k) is an integer.at n=24A078113
• Twin-prime-indexed primes (TWIPS): members of a pair of twin primes whose prime index is also a member of a pair of twin primes.at n=40A087373
• Smallest prime obtained as a sum of n terms of a geometric progression + the common ratio, or 0 if no such terms exists. Smallest prime of the form (a +ar +ar^2 + ar^3 +... ) + r.at n=11A088121
• a(n) = (A085249(n) - 1)/6.at n=23A088349
• Triangle read by rows: T(n,k) = number of peakless Motzkin paths of length n and containing a total of k level steps H in all DHH...HU's, where U=(1,1), H=(1,0) and D=(1,-1) (can be easily expressed using RNA secondary structure terminology).at n=51A097107
• Triangle read by rows: T(n,k) = number of peakless Motzkin paths of length n containing k DHH...HU's, where U=(1,1), D=(1,-1) and H=(1,0) (can be easily expressed using RNA secondary structure terminology).at n=27A098083
• Primes that are the sum of the squares of the first k primes for some k.at n=1A098562
• Largest prime p such that the sum of n consecutive primes plus p is equal to (n+1)^3.at n=26A100572
• Sum of n-th prime squared and n-th perfect square.at n=33A106587
• Least p=prime(k) for which A118123(k)=n.at n=35A117877
• Numerator of Sum[ Prime[k]^2, {k,1,n}] / Product[ Prime[k], {k,1,n}] = Numerator[ A024450[n] / A002110[n] ].at n=17A122136
• Primes from A122136 corresponding to the indices A122138.at n=11A122139
• The number of edges on a piece of paper that has been folded n times (see comments for more precise definition).at n=23A133257
• Primes congruent to 4 mod 59.at n=39A142731