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A154800 List of pairs of primes that are equidistant from and nearest to n, or the pair (0,0) if there is no such pair. 1
0, 0, 0, 0, 0, 0, 3, 5, 3, 7, 5, 7, 3, 11, 5, 11, 7, 11, 7, 13, 5, 17, 11, 13, 7, 19, 11, 17, 13, 17, 13, 19, 11, 23, 17, 19, 7, 31, 17, 23, 19, 23, 13, 31, 17, 29, 19, 29, 19, 31, 23, 29, 23, 31, 19, 37, 17, 41, 29, 31, 19, 43, 23, 41, 29, 37, 31, 37, 29, 41, 31, 41, 31, 43, 29, 47 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

Conjecture: There are only six 0's in this sequence.

LINKS

Table of n, a(n) for n=1..76.

EXAMPLE

Array begins:

n ............... Pair

1 .............. 0 . 0

2 .............. 0 . 0

3 .............. 0 . 0

4 .............. 3 . 5

5 ............ 3 . . . 7

6 .............. 5 . 7

7 ........ 3 . . . . . . . 11

8 .......... 5 . . . . . 11

9 ............ 7 . . . 11

10 ......... 7 . . . . . 13

MAPLE

A154800 := proc(n) local d; for d from 1 to n-1 do if isprime(n-d) and isprime(n+d) then printf("%d, %d, ", n-d, n+d); RETURN() ; fi; od: printf("0, 0, ") ; end: seq(A154800(n), n=1..80) ; # R. J. Mathar, Jul 13 2009

CROSSREFS

Cf. A154720, A154721, A154722, A154723, A154724, A154725, A154726, A154727.

Sequence in context: A144294 A255313 A305883 * A263175 A137768 A137769

Adjacent sequences:  A154797 A154798 A154799 * A154801 A154802 A154803

KEYWORD

nonn,tabf

AUTHOR

Omar E. Pol, Jan 15 2009, Jan 18 2009

EXTENSIONS

More terms from R. J. Mathar, Jul 13 2009

STATUS

approved

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Last modified April 21 14:42 EDT 2021. Contains 343154 sequences. (Running on oeis4.)