A279065 - OEIS

A279065

Fermi-Dirac primeth recurrence: a(0)=1; thereafter a(n+1) = a(n)-th number of the form p^(2^k) where p is prime and k>=0.

1, 2, 3, 4, 5, 7, 11, 19, 47, 169, 907, 6829, 67931, 851891, 13034887, 237522877, 5057212439, 123890683831

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OFFSET

0,2

COMMENTS

Daniel Forgues (see A182979) and Reinhard Zumkeller (see A213925) describe the increasing sequence of positive integers of the form p^(2^k) where p is prime and k>=0 (A050376 or A084400) as Fermi-Dirac primes, because any positive integer has a unique factorization into distinct terms.

LINKS

Table of n, a(n) for n=0..17.

OEIS Wiki, "Fermi-Dirac representation" of n.

MATHEMATICA

nn=10000; FDfactor[n_]:=If[n===1, {}, Sort[Join@@Cases[FactorInteger[n], {p_, k_}:>Power[p, Cases[Position[IntegerDigits[k, 2]//Reverse, 1], {m_}->2^(m-1)]]]]];

FDprimeList=Array[FDfactor, nn, 1, Union];

NestWhileList[Part[FDprimeList, #]&, 1, #<=Length[FDprimeList]&]

PROG

(PARI) lista(kmax) = {my(m = 1, c=0, isp); print1(1, ", "); for(k = 1, kmax, isp = isprimepower(k); if(isp && isp >> valuation(isp, 2) == 1, c++); if(c == m, print1(k, ", "); m=k)); } \\ Amiram Eldar, Oct 05 2023

CROSSREFS

Cf. A007097, A050376, A084400, A182979, A213925.

Sequence in context: A343305 A346076 A339357 * A327325 A340252 A324989

Adjacent sequences: A279062 A279063 A279064 * A279066 A279067 A279068

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, Dec 10 2016

EXTENSIONS

a(15)-a(17) from Amiram Eldar, Oct 05 2023

STATUS

approved