A107273 Vertically symmetrical dates MMDDYYYY (American notation) excluding years which are divisible by 10, considered as numbers, in increasing order.

10011001, 10025001, 10052001, 10088001, 10100101, 10111101, 10125101, 10152101, 10188101, 10200501, 10211501, 10225501, 10252501, 10288501, 11011011, 11025011, 11052011, 11088011, 11100111, 11111111, 11125111

Offset: 1

Author

Alexandre Wajnberg, May 19 2005

Keywords

• base
• easy
• fini
• full
• nonn

Comments

2 and 5 are taken as mirror images (as on calculator displays). a(1)=10011001 and a(20)=11111111 shared the property to present also two symmetrical halves.

This sequence has exactly 42 terms, ending with 12288551 (Dec. 28th 8551).

Links

• Iain Fox, Table of n, a(n) for n = 1..42

Crossrefs

Condensed American notation dates: A107274.

Metric convention dates: A107275.

Condensed European notation dates: A107276.

Cf. A053701, A106605.

Programs

PARI

a(n) = my(d=digits(126+25*((n-1)\14)+(n-1)%14, 5)); fromdigits(apply(i->[0, 1, 2, 5, 8, 5, 2][i+1], concat(d, apply(i->i+3*bitand(i, 2)/2, Vecrev(d))))) \\ Iain Fox, Jul 08 2022

Extensions

Definition clarified by Hieronymus Fischer, Apr 01 2012