23909

Properties

Appears in sequences

• Euler transform of 3 2 1 1 1 1 1 1...at n=20A029859
• a(1)=2; a(n) for n>1 is the smallest prime number > a(n-1) such that the concatenation of all previous terms is also prime.at n=34A080155
• Balanced primes of order four.at n=27A082079
• Primes A005382(n) + A005384(n) - 1 with a twin prime A005382(n) + A005384(n) + 1.at n=30A099109
• Prime numbers p such that primepi(p) + p is a square.at n=19A104269
• Let m = A002445(n); then a(n) = largest member of A001359 (the lesser twin primes sequence) <= m.at n=26A156053
• Number of toothpicks after n stages of 3-D toothpick structure defined in Comments.at n=32A170876
• Lesser of twin primes p1 such that p1+(p2^2-p1^2) and p2+(p2^2-p1^2) are prime numbers.at n=31A174922
• Final prime adjoined in the smallest term of A019518 divisible by 73^n.at n=1A185704
• G.f. satisfies: A(x) = 1 + x/A(-x*A(x)^6)^2.at n=7A213098
• The first member of a twin prime pair whose sum equals the sums of two consecutive smaller pairs of twin primes.at n=36A225943
• a(n) = the first member of a twin prime pair whose sum equals the sums of n consecutive pairs of twin primes.at n=22A226719
• Primes p such that p+2 and q are primes, where q is concatenation of binary representations of p and p+2: q = p * 2^L + p+2, where L is the length of binary representation of p+2: L=A070939(p+2).at n=34A232238
• Primes p with p + 2 and prime(p) - 2 both prime.at n=38A236467
• Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 446", based on the 5-celled von Neumann neighborhood.at n=7A272249
• Primes p = x^2 + y^2 such that x - y is a cube greater than one.at n=32A282405
• Number of n X 3 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=5A301836
• T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=33A301841
• Number of 6Xn 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=2A301846
• Number of nX6 0..1 arrays with every element equal to 1, 2, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.at n=4A302526