20478

Appears in sequences

• a(n) = 1^2 + prime(1)^2 + prime(2)^2 + ... + prime(n)^2.at n=18A024525
• a(n) = 5*2^n - 2.at n=12A051633
• Number of primes between successive Lucas numbers.at n=26A052012
• Triangle read by rows: T(n,k) = number of partitions of binomial(n,k) into parts greater than k and not greater than n, 0<=k<=n.at n=58A090824
• Number of palindromes (in base 4) below 4^n.at n=12A117863
• Start with 1, then alternately add 2 or double.at n=25A123208
• a(n) = 5*2^(n-2) - 2 for n > 1, with a(1) = 1.at n=13A131051
• Row sums of triangle A134061.at n=12A134062
• a(n) is the smallest number such that a(n)*n is an anagram of a(n)*5.at n=43A175694
• Initial members of abundant quadruplets, i.e., values of k such that (k, k+2, k+4, k+6) are all abundant numbers.at n=36A231089
• Indices of primes in the 7th-order Fibonacci number sequence, A060455.at n=42A253318
• Squarefree numbers n such that n^2 + 1 and n^2 - 1 are semiprime.at n=27A268697
• Start at a(0)=1. a(n) = a(n-1)+2 if n == 1,2 (mod 3) and a(n)=a(n-1)+a(n-3) if n == 0 (mod 3).at n=37A268896
• Numbers n such that n^1024 + (n+1)^1024 is prime.at n=33A274234
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 502", based on the 5-celled von Neumann neighborhood.at n=14A282684
• Number of set partitions of {1, 2, ..., n} such that, for any two numbers in the same part, one divides the other.at n=17A333517
• Expansion of Product_{k>=1} 1/((1 - x^(k^2))*(1 - x^k)).at n=26A369520
• Number of distinct n X n patterns in the squiral tiling.at n=36A375874