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!)
A088631 Largest number m < n such that m+n is a prime. 5
1, 2, 3, 2, 5, 6, 5, 8, 9, 8, 11, 10, 9, 14, 15, 14, 13, 18, 17, 20, 21, 20, 23, 22, 21, 26, 25, 24, 29, 30, 29, 28, 33, 32, 35, 36, 35, 34, 39, 38, 41, 40, 39, 44, 43, 42, 41, 48, 47, 50, 51, 50, 53, 54, 53, 56, 55, 54, 53, 52, 51, 50, 63, 62, 65, 64, 63, 68, 69, 68, 67, 66, 65, 74, 75 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

REFERENCES

F. W. Roush and D. G. Rogers, A prime algorithm?, preprint, 1999.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 2..10000

FORMULA

a(n) = p-n where p = largest prime <= 2n-1.

a(n) = A060265(n) - n. - Reinhard Zumkeller, Feb 22 2015

EXAMPLE

Adding 1,2,3,2,5 to 2,3,4,5,6 we get the primes 3,5,7,7,11.

MAPLE

with(numtheory); A088631 := n->prevprime(2*n)-n;

PROG

(Haskell)

a088631 n = a060265 n - n  -- Reinhard Zumkeller, Feb 22 2015

CROSSREFS

Cf. A088633. Second column of A088643.

Cf. A010051, A060265, A007917.

Sequence in context: A164912 A289386 A088861 * A086184 A056552 A049273

Adjacent sequences:  A088628 A088629 A088630 * A088632 A088633 A088634

KEYWORD

easy,nonn

AUTHOR

N. J. A. Sloane, Nov 24 2003

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 April 6 07:02 EDT 2020. Contains 333267 sequences. (Running on oeis4.)