

A203074


a(0)=1; for n > 0, a(n) = next prime after 2^(n1).


5



1, 2, 3, 5, 11, 17, 37, 67, 131, 257, 521, 1031, 2053, 4099, 8209, 16411, 32771, 65537, 131101, 262147, 524309, 1048583, 2097169, 4194319, 8388617, 16777259, 33554467, 67108879, 134217757, 268435459, 536870923, 1073741827, 2147483659
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OFFSET

0,2


COMMENTS

Equals {1} union A014210. Unlike A014210, every positive integer can be written in one or more ways as a sum of terms of this sequence. See A203075, A203076.


LINKS

M. F. Hasler & Bill McEachen, Table of n, a(n) for n = 0..1300 (missing lines n=1159..1165 from Bill McEachen)
Wikipedia, Complete sequence.


FORMULA

A203074(n) = 2^(n1) + A013597(n1), for n > 0.  M. F. Hasler, Mar 15 2012
a(n) = A104080(n1) for n > 2.  Georg Fischer, Oct 23 2018


EXAMPLE

a(5) = 17, since this is the next prime after 2^(51) = 2^4 = 16.


MATHEMATICA

nextprime[n_Integer] := (k=n+1; While[!PrimeQ[k], k++]; k); aprime[m_Integer] := (If[m==0, 1, nextprime[2^(m1)]]); Table[aprime[l], {l, 0, 100}]
nxt[{n_, a_}]:={n+1, NextPrime[2^n]}; NestList[nxt, {0, 1}, 40][[All, 2]] (* Harvey P. Dale, Oct 10 2017 *)


PROG

(PARI) a(n)=if(n, nextprime(2^n/2+1), 1) \\ Charles R Greathouse IV
(PARI) A203074(n)=nextprime(2^(n1)+1)!n \\ M. F. Hasler, Mar 15 2012
(Magma) [1] cat [NextPrime(2^(n1)): n in [1..40]]; // Vincenzo Librandi, Feb 23 2018


CROSSREFS

Cf. A013632, A013597, A014210, A104080, A203075, A203076.
Sequence in context: A298598 A079370 A014210 * A014556 A062737 A085613
Adjacent sequences: A203071 A203072 A203073 * A203075 A203076 A203077


KEYWORD

nonn


AUTHOR

Frank M Jackson and N. J. A. Sloane, Dec 28 2011


STATUS

approved



