A356421 - OEIS

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A356421

Positive integers k such that k + p is a power of 2, where p is the least prime greater than k.

3, 15, 61, 255, 2043, 4093, 32765, 65535, 262141, 8388599, 33554397, 134217699, 268435453, 1073741821, 17179869159, 137438953463, 274877906937, 1099511627761, 8796093022179, 17592186044409, 70368744177649, 140737488355323, 281474976710635, 562949953421243

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OFFSET

1,1

COMMENTS

The corresponding sequence of primes is the intersection of A014210 and A356434 without the initial 2.

LINKS

Table of n, a(n) for n=1..24.

EXAMPLE

3 + 5 = 8;

15 + 17 = 32;

61 + 67 = 128.

PROG

(Python)

from itertools import islice

from sympy import nextprime

def A356421_gen():

m = 1

while True:

n = m+1<<1

k = m

p = nextprime(k)

while k+p>n:

k -=1

p = nextprime(k)

if k+p==n:

yield k

m = n-1

A356421_list = list(islice(A356421_gen(), 30)) # Chai Wah Wu, Sep 11 2022

CROSSREFS

Cf. A000040, A000079, A014210, A356434.

Sequence in context: A292483 A218227 A072336 * A122671 A317181 A067562

Adjacent sequences: A356418 A356419 A356420 * A356422 A356423 A356424

KEYWORD

nonn

AUTHOR

Ali Sada, Aug 06 2022

EXTENSIONS

Terms from Tom Duff via Seqfan.

STATUS

approved