A094747 - OEIS

A094747

Rearrangement of odd primes so that absolute successive differences are the least distinct even numbers. Priority is given to the least successive difference that has not occurred earlier.

3, 5, 11, 7, 17, 29, 37, 23, 41, 61, 83, 67, 43, 71, 97, 127, 163, 131, 89, 137, 103, 59, 19, 73, 13, 79, 149, 199, 251, 307, 269, 223, 281, 349, 277, 353, 431, 367, 293, 373, 311, 229, 313, 227, 139, 47, 151, 241, 337, 239, 347, 449, 563, 463, 557, 673, 797, 691, 809

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

We interpret the definition as saying that we find a(n+1) from a(n) by testing a(n)-+2*d (first the minus, then the plus, d=1,2,3,4...., d not used before) for primality and for not already being on the list. This creates a list of odd primes, but there is no proof (yet) that all odd primes are in the sequence. - R. J. Mathar, Jul 29 2007

LINKS

Table of n, a(n) for n=1..59.

MAPLE

A094747 := proc(nmax) local a, diffs, d; a := [3] ; diffs := {} ; while nops(a) < nmax do d := 2 ; while true do if isprime(op(-1, a)-d) and not op(-1, a)-d in a and not abs(d) in diffs then a := [op(a), op(-1, a)-d] ; diffs := diffs union {d} ; break ; elif isprime(op(-1, a)+d) and not op(-1, a)+d in a and not abs(d) in diffs then a := [op(a), op(-1, a)+d] ; diffs := diffs union {d} ; break ; else d := d+2 ; fi ; od ; od; RETURN(a) ; end: A094747(100) ; # R. J. Mathar, Jul 29 2007

CROSSREFS

Cf. A094748.

Sequence in context: A225487 A145398 A087322 * A300783 A359115 A287939

Adjacent sequences: A094744 A094745 A094746 * A094748 A094749 A094750

KEYWORD

nonn

AUTHOR

Amarnath Murthy, May 24 2004

EXTENSIONS

More terms from R. J. Mathar, Jul 29 2007

STATUS

approved