20641

Properties

Appears in sequences

• Primes that divide at least one term of Sylvester's sequence s = A000058: s(n+1) = s(n)^2 - s(n) + 1, s(0) = 2.at n=34A007996
• Consider all ways of writing a number as p+2m^2 where p is 1 or a prime and m >= 0; sequence gives numbers that are expressible in at least 2 more ways than any smaller number.at n=15A016067
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 86 ones.at n=25A031854
• Triangle of coefficients of generating function of 5-ary rooted trees of height at most n.at n=62A036607
• Number of 5-ary rooted trees with n nodes and height at most 4.at n=20A036615
• Smallest integer that can be expressed as p+2m^2 in more ways than any smaller number, where m >= 0 and p = 1 or prime.at n=36A055202
• Primes p for which the period of reciprocal = (p-1)/8.at n=32A056213
• Minimal set in the sense of A071062 of prime-strings in base 12 for primes of the form 4n+1.at n=31A111057
• Numbers k such that k, k+1, k+2 and k+3 are 1,2,3,4-almost primes.at n=20A113000
• Largest prime divisor of Fibonacci(5n).at n=23A121170
• Largest prime divisor of Lucas(5*n), where Lucas(k) = A000032(k).at n=11A121171
• Least k such that the difference between consecutive semiprimes A065516(k) equals n, or 0 if no such k exists.at n=35A123375
• a(n) = 5*a(n-2) + 2*a(n-3).at n=14A135138
• Primes congruent to 50 mod 59.at n=38A142777
• Primes congruent to 23 mod 61.at n=38A142821
• Conjectured row or column n=4 of array A205497.at n=4A205494
• Triangle read by rows: Zig-zag Eulerian number triangle T(n, k).at n=42A205497
• Greatest prime factor of n^5 + 1.at n=39A240548
• Those terms of A255571 whose every A080541/A080542-rotation is also a term of A255571.at n=35A258001
• Primes p such that both 2p-1 and 2p^2-2p+1 are prime.at n=23A274609