A106605 Vertically symmetrical dates DDMMYYYY excluding years which are divisible by 10, considered as numbers, in increasing order.

10011001, 10025001, 10052001, 10088001, 10100101, 10111101, 10125101, 11011011, 11025011, 11052011, 11088011, 11100111, 11111111, 11125111, 12011051, 12025051, 12052051, 12088051, 12100151, 12111151, 12125151, 15011021, 15025021, 15052021

Offset: 1

Author

Nicolas Graner, Eric Angelini and Alexandre Wajnberg, May 10 2005

Keywords

• base
• easy
• fini
• full
• nonn

Comments

2 and 5 are taken as mirror images (as on calculator displays). a(1)=10011001, a(13)=11111111 and a(38)=20052005 (May 20 2005!) also share the unique property of having two symmetrical halves.

This sequence has exactly 70 terms, ending with 28125185 (Dec 28 5185).

Links

• Nathaniel Johnston, Table of n, a(n) for n = 1..70 (full sequence)

Crossrefs

Cf. A053701.

Programs

Maple

compdig := proc(n) if(n=2)then return 5: elif(n=5)then return 2: elif(n=0 or n=1 or n=8)then return n: else return -1: fi: end: for d from 10 to 28 do for m from 1 to 12 do for y from 1 to 8888 do dt:=1000000*d+10000*m+y: dig:=convert(dt,base,10): if(dig[1]=compdig(dig[8]) and dig[2]=compdig(dig[7]) and dig[3]=compdig(dig[6]) and dig[4]=compdig(dig[5]))then print(dt): fi: od: od: od: # Nathaniel Johnston, May 17 2011

Extensions

Definition clarified by Hieronymus Fischer, Apr 01 2012