25771

Properties

Appears in sequences

• When squared gives number composed of digits {1,4,6}.at n=18A027677
• Numbers n such that h(n) = 3 h(n-1) where h(n) is the length of the sequence {n, f(n), f(f(n)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=28A078420
• Primes p such that p + googol is prime.at n=20A108250
• Primes p such that p+1, p+2 and p+3 have equal number of divisors.at n=29A119711
• Number of nXnXn triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= 6.at n=7A166201
• Number of 7X7X7 triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= n.at n=6A166215
• Primes p such that (53^p - 1)/52 is also prime.at n=4A173767
• Primes p such that 2p^2-1, 3p^2-2 and 4p^2-3 are also prime.at n=10A213079
• T(n,k)=Majority value maps: number of nXk binary arrays indicating the locations of corresponding elements equal to at least half of their horizontal, diagonal and antidiagonal neighbors in a random 0..1 nXk array.at n=30A220226
• Majority value maps: number of 3Xn binary arrays indicating the locations of corresponding elements equal to at least half of their horizontal, diagonal and antidiagonal neighbors in a random 0..1 3Xn array.at n=5A220228
• a(n) is the smallest start of a run of exactly n consecutive primes such that the sum of the digits of each prime is composite.at n=10A241525
• Number of Dyck paths of semilength n having exactly 9 (possibly overlapping) occurrences of the consecutive steps UDUUDU (with U=(1,1), D=(1,-1)).at n=4A243421
• a(n) = Sum_{k=0..3} binomial(6,k)*binomial(n,k).at n=20A247608
• Primes p such that 2*p+1 is divisible by the sum of digits of p+1.at n=41A267542
• a(n) is the largest prime factor of the concatenation of a(n-2) and a(n-1), with a(1)=1 and a(2)=2.at n=7A280894
• The first prime of 8 consecutive primes a, b, c, d, e, f, g, h such that a + g = c + e and b + h = d + f.at n=24A292618
• a(n) is the smallest prime p such that the Hankel matrix of the 2*n-1 consecutive primes starting at p is singular; a(n) = 0 if no such p exists.at n=2A350201
• Prime numbersat n=2838