27581

Properties

Appears in sequences

• a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (Lucas numbers).at n=15A024469
• a(n) = s(1)*s(n) + s(2)*s(n-1) + ... + s(k)*s(n-k+1), where k = [n/2], s = (Lucas numbers).at n=15A025089
• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 66.at n=2A031654
• Smallest prime p having n different cycles in decimal expansions of k/p, k=1..p-1.at n=34A054471
• 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=24A058056
• One half of second column of Lucas bisection triangle (odd part).at n=7A061171
• Convolution of L(n+1) := A000204(n+1) (Lucas), n>=0, with L(n+9), n>=0.at n=7A067987
• Records in A079387.at n=14A079388
• 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, 0, 1), (-1, 1, 0), (1, -1, 1), (1, 0, 0), (1, 1, -1)}.at n=9A148749
• Primes p such that p^3 - 12 and p^3 + 12 are also primes.at n=31A153322
• a(1) = 3. For n > 1, Ulam's spiral is started with a(n-1), and the primes p on the NE spoke are considered. a(n) is the minimal p that is the lesser of a twin prime pair.at n=31A163586
• Lesser of twin primes p1 such that p1+(p2^2-p1^2) and p2+(p2^2-p1^2) are prime numbers.at n=34A174922
• Primes of the form k^2 + 25.at n=39A346145
• Positions of records in A205561.at n=32A378189
• Primes p such that p+1 is a triprime and 2*p+1 is prime.at n=43A386295
• Prime numbersat n=3011