19739

Properties

Appears in sequences

• Primes p such that p-12, p and p+12 are consecutive primes.at n=16A053072
• Primes with all odd digits such that the next three primes also contain all odd digits.at n=18A068831
• Numbers k such that h(k) = h(k-1) + h(k-2), where h(k) = A006577(k) + 1 is the length of the sequence {k, f(k), f(f(k)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=37A078418
• Primes p such that p's set of distinct digits is {1,3,7,9}.at n=14A108386
• Prime Friedman numbers.at n=15A112419
• Primes congruent to 36 mod 61.at n=35A142834
• Primes of the form 4*n^2 + 2*n -1.at n=34A155737
• Primes of the form (p^2-1)/4-p where p are also primes.at n=22A165557
• Primes of the form p^2 +3p + 1, where p is also a prime.at n=15A165944
• Numbers with d digits (d>0) which have at least 2d distinct primes as substrings.at n=11A168167
• Primes with nine embedded primes.at n=1A179917
• Prime numbers > 10000 such that all the substrings of length >= 4 are primes (substrings with leading '0' are considered to be nonprime).at n=32A211686
• Primes p such that p^4 + p + 1 and p^4 - p - 1 are also prime.at n=15A236073
• Primes of the form n^2-n-1 (for some n) such that p^2-p-1 is also prime.at n=16A237642
• Triangle read by rows: T(n,k) = number of normal planar lambda terms of size n with k free variables (n >= 1, 1 <= k <= n).at n=22A246323
• Primes among "orderly" Friedman numbers A080035.at n=3A252483
• Primes of the form sigma(n) + sigma(n)^2 - 1.at n=39A259190
• The integer part of the surface area of the 4-dimensional sphere of radius n.at n=9A261791
• a(n) = 137*n^2 - 4043*n + 27277.at n=2A267706
• Number of ways to tile an n X n X n triangular area with three 2 X 2 X 2 triangular tiles and an appropriate number (= n^2-12) of 1 X 1 X 1 tiles.at n=6A286438