A117129 Primes not occurring as |differences| in Cald's sequence A006509.

641, 1213, 2617, 2957, 3727, 5443, 9283, 17359, 33829, 66173, 131303, 264763, 494743, 957547, 1888157, 3753647, 7490797, 14961157, 29899357, 59773871, 119551489, 239106347, 478234723, 956607929, 1913366111, 3826828409, 7653840367, 15308666783, 30619196381, 57415599151

Offset

1,1

Comments

In other words, primes that do not occur as absolute values of differences of successive terms in Cald's sequence A006509.

Links

Table of n, a(n) for n=1..30.

Formula

a(n) = prime(A112877(n) - 1).

Prog

(Python)
from itertools import count, islice
from sympy import nextprime
def A117129_gen(): # generator of terms
    a, aset, p = 1, {1}, 2
    for c in count(2):
        if (b:=a-p) > 0 and b not in aset:
            a = b
        elif (b:=a+p) not in aset:
            a = b
        else:
            a = 0
            yield p
        aset.add(a)
        p = nextprime(p)
A117129_list =  list(islice(A117129_gen(), 10)) # Chai Wah Wu, Mar 04 2024

Crossrefs

Cf. A006509, A112877.

Sequence in context: A252433 A252434 A105130 * A106488 A259997 A256806

Adjacent sequences: A117126 A117127 A117128 * A117130 A117131 A117132

Keyword

nonn

Author

N. J. A. Sloane, Apr 20 2006

Extensions

a(19)-a(26) from Donovan Johnson, Feb 18 2010

a(27)-a(29) from Chai Wah Wu, Mar 04 2024

a(30) from Chai Wah Wu, Mar 10 2024

Status

approved