cp's OEIS Frontend

A133650 Early early bird numbers (early bird numbers of order 2).

%I A133650 #10 Jul 01 2025 10:43:49
%S A133650 99,111,122,123,132,142,152,162,172,182,192,211,212,214,215,216,217,
%T A133650 218,219,220,221,231,232,233,234,243,253,263,273,283,293,311,312,313,
%U A133650 321,322,323,325,326,327,328,329,330,331,332,342,343,344,345,354,364,374
%N A133650 Early early bird numbers (early bird numbers of order 2).
%C A133650 N-th Early bird number A116700(n) is in the sequence if it occurs in the concatenation of the first n-1 early bird numbers, A116700(1), ..., A116700(n-1).
%C A133650 With A116700 as early bird numbers of order 1, this can be generalized to define early bird numbers of order k for k > 1: N-th Early bird number of order k-1 is an early bird number of order k if it occurs in the concatenation of the first n-1 early bird numbers of order k-1.
%C A133650 Inspired by Eric Angelini's posting to Seq Fan mailing list, Jul 23 2007.
%H A133650 Klaus Brockhaus, <a href="/A133650/b133650.txt">Table of n, a(n) for n = 1..1000</a>
%e A133650 A116700(45) = 99 occurs in the concatenation 1221233132344142434551525354566162636465677172737475767881828384858687899192939495969798 of A116700(1), ..., A116700(44). Hence 99 is an early bird number of order 2.
%o A133650 (JBASIC)
%o A133650 REM Program works for order >= 1; set maxterm >= A133652(order).
%o A133650 order = 2
%o A133650 maxterm = 374 : dim seq(maxterm), early(maxterm)
%o A133650 for i = 1 to maxterm : seq(i) = i : next
%o A133650 for k = 1 to order
%o A133650 concatenation$ = "" : n = 0
%o A133650 for j = 1 to maxterm
%o A133650 term = seq(j) : string$ = str$(term)
%o A133650 if instr(concatenation$, string$) > 0 then n = n+1 : early(n) = term
%o A133650 concatenation$ = concatenation$ + string$
%o A133650 next j
%o A133650 maxterm = n : redim seq(maxterm)
%o A133650 for i = 1 to maxterm : seq(i) = early(i) : next
%o A133650 redim early(maxterm)
%o A133650 next k
%o A133650 print "early bird numbers of order "; order
%o A133650 for i = 1 to maxterm : print seq(i); ","; : next
%Y A133650 Cf. A116700 (early bird numbers), A133651 (early bird numbers of order 3), A133652 (least early bird number of order n).
%K A133650 nonn,base
%O A133650 1,1
%A A133650 _Klaus Brockhaus_, Sep 19 2007