A082270 - OEIS

A082270

a(1) = 1; for n >= 1, a(n+1) = smallest number not occurring earlier such that a(n)*a(n+1) + 1 is a palindrome.

1, 2, 3, 7, 14, 10, 11, 21, 23, 32, 5, 13, 17, 29, 9, 6, 20, 8, 4, 19, 18, 28, 27, 22, 16, 34, 98, 135, 51, 146, 110, 101, 100, 102, 73, 220, 56, 131, 67, 43, 15, 12, 26, 38, 35, 181, 202, 50, 31, 215, 54, 111, 1891, 386, 45, 153, 130, 80, 125, 84, 398, 251, 70, 150, 68

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..65.

EXAMPLE

a(51)=54; 54*1 + 1 = palindrome 55 but 1 occurs already at a(1); next 54*11 + 1 = 595 but 11 occurs already at a(7); next 54*14 + 1 = 757 but 14 occurs at a(5); next 54*17 + 1 = 919 but 17 occurs at a(13); ...; finally 54*111 + 1 = 5995 and 111 did not yet occur so 111 is included as next term a(52).

CROSSREFS

Cf. A081941, A082271.

Sequence in context: A372229 A073827 A081940 * A055688 A241583 A081941

Adjacent sequences: A082267 A082268 A082269 * A082271 A082272 A082273

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Apr 02 2003, Apr 14 2003

EXTENSIONS

More terms from Patrick De Geest, Jun 09 2003

Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 09 2007

STATUS

approved