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A243591 Numbers n such that floor((3/2)^n)-floor((3/2)^(n-1)) is a prime number. 0
4, 5, 9, 10, 11, 12, 14, 19, 20, 32, 47, 89, 96, 105, 123, 143, 291, 354, 371, 424, 493, 526, 784, 906, 2670, 3506, 7096, 7938, 15046, 23959, 24920, 51182 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(33) > 4 * 10^5. - Lucas A. Brown, Nov 26 2020

LINKS

Table of n, a(n) for n=1..32.

MATHEMATICA

Flatten[Position[Partition[Floor[(3/2)^Range[51200]], 2, 1], _?(PrimeQ[ #[[2]] -  #[[1]]]&), 1, Heads->False]]+1 (* Harvey P. Dale, May 17 2021 *)

PROG

(PFGW & SCRIPT)

SCRIPT

DIM k, 1

DIM q

OPENFILEOUT myf, a(n).txt

LABEL loop1

SET k, k+1

SET q, 3^k/2^k-3^(k-1)/2^(k-1)

PRP q

IF ISPRP THEN GOTO a

GOTO loop1

LABEL a

WRITE myf, k

GOTO loop1

CROSSREFS

Cf. A242734, A242738.

Sequence in context: A172180 A193959 A093667 * A189012 A030415 A120516

Adjacent sequences:  A243588 A243589 A243590 * A243592 A243593 A243594

KEYWORD

nonn,more,hard

AUTHOR

Pierre CAMI, Jun 07 2014

STATUS

approved

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Last modified June 15 11:10 EDT 2021. Contains 345048 sequences. (Running on oeis4.)