20089

Properties

Appears in sequences

• Boustrophedon transform of triangular numbers 1,1,3,6,10,...at n=8A000718
• Numbers k such that the continued fraction for sqrt(k) has period 53.at n=26A020392
• Smallest nonempty set S containing prime divisors of 5k+8 for each k in S.at n=26A020600
• a(n) = (1/2)*s(n+3), where s = A025244.at n=11A025245
• Numbers k such that k^2 contains exactly 9 different digits.at n=36A054037
• Prime lucky numbers k (from A031157) such that nextprime(k)=nextlucky(k).at n=26A057698
• Triangle T(n,k) of numbers with e.g.f. exp((exp((1+x)*y)-1)/(1+x)), k=0..n-1.at n=31A059340
• For n > 1, a(n) is the smallest number such that n-th concatenation is prime and the smallest palindrome beginning with (but not equal to) this concatenation is also prime.at n=14A088090
• Number of distinct products i*j*k*l for 1 <= i < j < k < l <= n.at n=41A100438
• Consider primes p such that integer part of the volume of cube with faces of area p is prime; sequence gives integer part of volumes.at n=13A107989
• Numbers k such that binomial(4k, k) + 1 is prime.at n=30A125241
• Primes congruent to 20 mod 61.at n=32A142818
• a(n) = 62*n^2 + 1.at n=18A158676
• Primes p such that q*p+-Mod(p,q) are primes, for q=7.at n=28A178387
• a(n) = 12*n^2 - 2*n - 1.at n=41A185918
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 446", based on the 5-celled von Neumann neighborhood.at n=34A272250
• Consider Watanabe's 3-shift tag system {00/1011} applied to the word (100)^n; a(n) = position of the longest word in the orbit, or -1 if the orbit is unbounded.at n=31A292094
• Number of nX3 0..1 arrays with every element equal to 1, 3, 4, 5, 6, 7 or 8 king-move adjacent elements, with upper left element zero.at n=9A300141
• Primes p such that A001175(p) = (p-1)/9.at n=8A308794
• Primes that yield squares after deletion of their zero digits.at n=12A321151