

A092696


Smoothly undulating palindromic primes of the form (12*10^n21)/99.


4




OFFSET

1,1


COMMENTS

The De Geest link calls these smoothly undulating palindromic primes. Corresponding n are given in A062209. Equivalently, primes of the form 1212...121: Decimal digits "12" repeated k times with 1 appended (or "21" repeated k times with 1 prefixed). Corresponding k are given in A056803. The next term, a(4), has "12" repeating A056803(4) = 69 times and length A062209(4) = 2*A056803(4) + 1 = 139 decimal digits.


LINKS

Table of n, a(n) for n=1..3.
P. De Geest, SUPP Reference Table
Index entries for sequences related to smoothly undulating palindromic primes


FORMULA

a(n) = (4*10^A062209(n)7)/33.  M. F. Hasler, Jul 30 2015


CROSSREFS

Cf. A056803 (number of 12's (or 21's)), A062209 (corresponding decimal digit lengths).
Cf. A032758, A033619, A030291, A059168, A242541, A004022.
Sequence in context: A251166 A274833 A206042 * A203627 A235910 A234997
Adjacent sequences: A092693 A092694 A092695 * A092697 A092698 A092699


KEYWORD

bref,nonn,base


AUTHOR

Rick L. Shepherd, Mar 04 2004


EXTENSIONS

Edited by M. F. Hasler, Jul 30 2015


STATUS

approved



