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A203985 Lexicographically earliest permutation of the primes such that successive absolute differences yield a permutation of all nonprime numbers. 2
2, 3, 13, 47, 197, 11, 29, 443, 397, 1321, 4831, 15559, 211, 5, 19, 41, 293, 113, 971, 419, 2687, 1087, 1709, 5851, 23629, 83, 17341, 65171, 268969, 20753, 690607, 4273, 1289, 81931, 56267, 3025961, 6343, 41927, 1455241, 14255011, 21557, 733, 44351, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It is only conjectured that this sequence is a permutation of the primes and that the successive differences yield all composite integers. The definition is rather to be understood as "The next term is chosen as the smallest prime not occurring earlier such that the successive absolute differences only yield 1 or composite numbers, and none of these occurs twice." - M. F. Hasler, Jan 09 2012

LINKS

J.-M. Falcoz, Table of n, a(n) for n = 1..70

E. Angelini, An array of naturals, Jan 07 2012

E. Angelini, An array of naturals  [Cached copy, with permission]

PROG

(PARI) {extend_first_row(a=[], u=[])=u||for(i=1, #a, u=setunion(u, Set(a[i])); forstep(j=i-1, 1, -1, u=setunion(u, Set(a[j]=abs(a[j]-a[j+1]))))); for(t=1, 9e9, isprime(t)||next; setsearch(u, t)&&next; my(tt=t, new=Set(t)); forstep(j=#a, 1, -1, setsearch(u, tt=abs(tt-a[j]))&&next(2); isprime(tt)&&next(2); setsearch(new, tt)&&next(2); new=setunion(new, Set(tt))); return(t))} \\ M. F. Hasler, Jan 09 2012

CROSSREFS

Sequence in context: A206776 A275556 A214888 * A164511 A184256 A105050

Adjacent sequences:  A203982 A203983 A203984 * A203986 A203987 A203988

KEYWORD

nonn

AUTHOR

Eric Angelini, Jan 07 2012

EXTENSIONS

First 70 terms computed by Jean-Marc Falcoz, Jan 09 2012

STATUS

approved

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Last modified August 21 00:36 EDT 2017. Contains 290855 sequences.