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A264849
a(n) is least number > 0 such that the concatenation of a(1) ... a(n) is 23-gonal: (21n^2 - 19n)/2.
6
1, 30, 648, 6701456, 72020220595275, 970458695858595792221157266, 3377345920936319088412440649783459968197698452784332095, 7477788200541027929765479736500643733301085903714718188060185368351929896324223859775571543015918781111399506
OFFSET
1,2
LINKS
EXAMPLE
1, 130, 130648 are 23-gonal.
PROG
(PARI) icositrigonal(n)=ispolygonal(n, 23)
first(m)=my(s=""); s="1"; print1(1, ", "); for(i=2, m, n=1; while(!icositrigonal(eval(concat(s, Str(n)))), n++); print1(n, ", "); s=concat(s, Str(n)))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Anders Hellström, Nov 26 2015
EXTENSIONS
a(5)-a(8) from Chai Wah Wu, Mar 15 2018
STATUS
approved