Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #18 May 19 2019 19:44:40
%S 0,1,2,3,4,5,6,102616333034,102620103253,103055445560,206154633166,
%T 206154633200,212216263215,212220033434,315315450515,321340554340,
%U 424436332033,424440102253,430461435550,430501403606,533560623156,533600556144
%N Numbers k such that k is the substring identical to the most significant digits of its base-7 representation.
%C Numbers k whose base-7 representation begins with the same digits as k itself.
%H Scott R. Shannon, <a href="/A308070/b308070.txt">Table of n, a(n) for n = 1..500</a>
%e 102616333034_10 = 10261633303415_7, which also begins with '102616333034'.
%o (PARI) isok(n) = my(vb=digits(n, 7), vd=digits(n)); vd == vector(#vd, k, vb[k]); \\ _Michel Marcus_, May 17 2019
%Y This is a subsequence of A228050.
%Y See A181929, A307254, A307255, A307256, A307257, A308071, A308072 for other bases.
%K nonn,base
%O 1,3
%A _Scott R. Shannon_, May 11 2019