A210887 Number of days after Mar 01 00 such that the date written in the format DD.MM.YY is palindromic.

619, 994, 1369, 3897, 4272, 4648, 7551, 7926, 8301, 11204, 11579, 11955, 14858, 15233, 15608, 18511, 18886, 19262, 22165, 22540, 22915, 25818, 26193, 26569, 29472, 29847, 30222, 33125, 33500, 33876

Offset: 1

Author

Hieronymus Fischer, Apr 01 2012

Keywords

• nonn
• base

Comments

There are exactly 30 such palindromic dates between Jan 01 00 and Dec 31 99 (see b-file for the complete list).

See A210888 for the corresponding dates.

The reference date Mar 01 00 makes sense, since this result in a sequence which is independent from the leap year / non-leap year property of the reference year "00".

Examples

			The first palindromic date in DD.MM.YY format after "Jan 01 00" is A210888(1)=101101 (="10.11.01"= "Nov 10 01" = "Mar 01 00" + 619 days);
The sixth palindromic date in DD.MM.YY format after "Jan 01 00" is A210888(6)=211112 (="21.11.12"= "Nov 21 12" = "Mar 01 00" + 4648 days).
The last (30th) palindromic date in DD.MM.YY format after "Jan 01 00" is A210888(30)=291192 (="29.11.92"= "Nov 29 92" = "Mar 01 00" + 33876 days).
		

Links

• Hieronymus Fischer, Table of n, a(n) for n = 1..30
• Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,1,-1).

Crossrefs

Cf. A210883-A210886, A210888-A210895, A106605, A107273, A107275.

Formula

From Chai Wah Wu, Feb 03 2021: (Start)

a(n) = a(n-1) + a(n-6) - a(n-7) for n > 10.

G.f.: x*(375*x^9 + 2284*x^6 + 376*x^5 + 375*x^4 + 2528*x^3 + 375*x^2 + 375*x + 619)/(x^7 - x^6 - x + 1). (End)