

A073924


Smallest power of 2 that is greater than the previous term such that every partial sum (n>1) is a prime.


7




OFFSET

1,2


COMMENTS

Next term 2^1752 is too large to include.


LINKS

Table of n, a(n) for n=1..9.


EXAMPLE

a(5) is 128 because it is the next power of 2 greater than 16 such that 1 + 2 + 4 + 16 + x is prime.


MATHEMATICA

a[1] = 1; a[n_] := Block[{k = a[n  1] + 1, s = Plus @@ (2^Array[a, n  1])}, While[ !PrimeQ[s + 2^k], k++ ]; k]; Array[2^a[ # ] &, 9] (* Robert G. Wilson v, Jan 31 2006 *)


CROSSREFS

Cf. A073923.
Sequence in context: A179532 A217994 A174677 * A061588 A202360 A050472
Adjacent sequences: A073921 A073922 A073923 * A073925 A073926 A073927


KEYWORD

nonn


AUTHOR

Amarnath Murthy, Aug 19 2002


EXTENSIONS

More terms from Jason Earls, Sep 03 2002


STATUS

approved



