login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A264842 a(n) is least number > 0 such that the concatenation of a(1) ... a(n) is 13-gonal: (11n^2 - 9n)/2. 6

%I #23 Jan 23 2017 13:08:10

%S 1,3,36,54765,123152388,374848814886363636,

%T 85794018663817263665487289502938826,

%U 107072047880615405294526336549204869795454545454545454545454545454545466

%N a(n) is least number > 0 such that the concatenation of a(1) ... a(n) is 13-gonal: (11n^2 - 9n)/2.

%H Jon E. Schoenfield, <a href="/A264842/b264842.txt">Table of n, a(n) for n = 1..11</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Polygonal_number">Polygonal number</a>

%e 1, 13, 1336, 133654765 are 13-gonal.

%o (PARI) tridecagonal(n)=ispolygonal(n, 13)

%o first(m)=my(s=""); s="1"; print1(1, ", "); for(i=2, m, n=1; while(!tridecagonal(eval(concat(s, Str(n)))), n++); print1(n, ", "); s=concat(s, Str(n)))

%Y Cf. A051671, A051865 (13-gonal numbers), A061109, A061110, A261696, A264733, A264738, A264776, A264777, A264848, A264849, A264804.

%K nonn,base

%O 1,2

%A _Anders Hellström_, Nov 26 2015

%E More terms from _Jon E. Schoenfield_, Nov 27 2015

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 06:44 EDT 2024. Contains 371265 sequences. (Running on oeis4.)