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Prime numbers that occupy prime-numbered positions
Super-prime numbers, also known as higher-order primes or prime-indexed primes (PIPs), are the subsequence of prime numbers that occupy prime-numbered positions within the sequence of all prime numbers. In other words, if prime numbers are matched with ordinal numbers, starting with prime number 2 matched with ordinal number 1, then the primes matched with prime ordinal numbers are the super-primes.
The subsequence begins
That is, if p(n) denotes the nth prime number, the numbers in this sequence are those of the form p(p(n)).
n 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 p(n) 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 p(p(n)) 3 5 11 17 31 41 59 67 83 109 127 157 179 191 211 241 277 283 331 353In 1975, Robert Dressler and Thomas Parker used a computer-aided proof (based on calculations involving the subset sum problem) to show that every integer greater than 96 may be represented as a sum of distinct super-prime numbers.[1] Their proof relies on a result resembling Bertrand's postulate, stating that (after the larger gap between super-primes 5 and 11) each super-prime number is less than twice its predecessor in the sequence.
A 2009 research showed that there are
super-primes up to x.[2] This can be used to show that the set of all super-primes is small.[3]
One can also define "higher-order" primeness much the same way and obtain analogous sequences of primes.[4]
A variation on this theme is the sequence of prime numbers with palindromic prime indices, beginning with
classes
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