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

Author

N. J. A. Sloane, Mar 14 2011

Keywords

• nonn
• base

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

• Claudio Meller, Lineas con numeros de 1 a n.
• Rémy Sigrist, PARI program for A187871

Crossrefs

Cf. A051237, A187869.

Programs

PARI

See Links section.

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