A187871 a(1)=1; for n > 1, a(n) is the smallest number that is formed by arranging the decimal numbers "1", "2", ..., "n" in some order so that the sum of every pair of adjacent numbers "i" "j" is prime.

1, 12, 123, 1234, 14325, 143256, 1234765, 12347658, 123476589, 10123476589, 1103211658947, 101121123476589, 11013432111276589, 1011211231458941367, 110134151432111276589, 10112112151431613476589, 1101316151417121123476589, 101121118131615141723476589

Offset

1,2

Comments

A051237 and A187869 are the sequence that result if in addition we require that the number begins with "1" and ends with "n".

Links

Table of n, a(n) for n=1..18.

Claudio Meller, Lineas con numeros de 1 a n.

Rémy Sigrist, PARI program for A187871

Prog

(PARI) See Links section.

Crossrefs

Cf. A051237, A187869.

Sequence in context: A262576 A362119 A262575 * A187869 A362117 A262574

Adjacent sequences: A187868 A187869 A187870 * A187872 A187873 A187874

Keyword

nonn,base

Author

N. J. A. Sloane, Mar 14 2011

Extensions

a(6) to a(10) from Claudio Meller, Mar 14 2011

a(10) corrected by Nathaniel Johnston, Mar 15 2011

More terms from Rémy Sigrist, Nov 28 2021

Status

approved