login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A272816 Prime pairs of the form (p, p+20). 3
3, 23, 11, 31, 17, 37, 23, 43, 41, 61, 47, 67, 53, 73, 59, 79, 83, 103, 89, 109, 107, 127, 131, 151, 137, 157, 173, 193, 179, 199, 191, 211, 251, 271, 257, 277, 263, 283, 293, 313, 311, 331, 317, 337, 347, 367, 353, 373, 359, 379, 389, 409, 401, 421 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

p and p+20 are not necessarily consecutive primes: (887, 907) is the first pair of consecutive primes that belongs to the sequence.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

FORMULA

a(2n+1) = A153419(n+1).

EXAMPLE

The prime pairs are (3, 23), (11, 31), (17, 37) etc.

MATHEMATICA

Flatten[{#, # + 20}&/@Select[Prime[Range[200]], PrimeQ[# + 20] &]]

PROG

(MAGMA) &cat [[p, p+20]: p in PrimesUpTo(1000) | IsPrime(p+20)];

(Python)

from gmpy2 import is_prime

for n in range(1000):

   if(is_prime(n) and is_prime(n+20)):

      print('{}, {}'.format(n, n+20), end=', ')

# Soumil Mandal, May 14 2016

CROSSREFS

Cf. A000040, A153419.

Cf. similar sequences listed in A272815.

Prime pairs of the form (p, p+k): A077800 (k=2), A094343 (k=4), A156274 (k=6), A156320 (k=8), A140445 (k=10), A156323 (k=12), A140446 (k=14), A272815 (k=16), A156328 (k=18), this sequence (k=20), A140447 (k=22).

Sequence in context: A196083 A285098 A088605 * A063562 A130475 A212998

Adjacent sequences:  A272813 A272814 A272815 * A272817 A272818 A272819

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, May 07 2016

EXTENSIONS

Edited by Bruno Berselli, May 12 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 6 04:14 EST 2021. Contains 341841 sequences. (Running on oeis4.)