A071066 Palindromic prime pyramid with a(1)=2 such that (number of digits in a(n+1)) = (number of digits in a(n)) + 6.

2, 3002003, 3303002003033, 9303303002003033039, 7609303303002003033039067, 3007609303303002003033039067003, 9003007609303303002003033039067003009, 3819003007609303303002003033039067003009183

Offset

1,1

Comments

G. L. Honaker Jr. and C. Caldwell conjectured that this pyramid has a finite number of terms (about 193 terms).

This pyramid is only an example of such a pyramid and is not the least possible (because otherwise we would have a(2)=102201), nor is it the tallest known pyramid expanding by 6 digits at each step (see Rivera link). - Sean A. Irvine, Jun 26 2024

References

G. L. Honaker Jr. and C. Caldwell, Palindromic prime pyramids. J.Recreational mathematics, vol. 30.3, pp. 169-176,1999-2000

J.-P. Delahaye, "Pour la science", (French edition of Scientific American), Juin 2002, p. 99

Links

Table of n, a(n) for n=1..8.

C. Rivera, Puzzle 1143, Problems & Puzzles

Crossrefs

Cf. A070927, A070922.

Sequence in context: A037051 A283072 A214599 * A337368 A137601 A232962

Adjacent sequences: A071063 A071064 A071065 * A071067 A071068 A071069

Keyword

easy,nonn,base,changed

Author

Benoit Cloitre, May 26 2002

Status

approved