A073924 Smallest power of 2 that is greater than the previous term such that every partial sum (n>1) is a prime.

1, 2, 4, 16, 128, 65536, 9007199254740992, 73786976294838206464, 205688069665150755269371147819668813122841983204197482918576128

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 * A362065 A061588 A202360

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