login
Powers of 2 with initial digit 6.
4

%I #17 Sep 08 2022 08:46:23

%S 64,65536,67108864,68719476736,604462909807314587353088,

%T 618970019642690137449562112,633825300114114700748351602688,

%U 649037107316853453566312041152512,664613997892457936451903530140172288,680564733841876926926749214863536422912

%N Powers of 2 with initial digit 6.

%H Muniru A Asiru, <a href="/A320862/b320862.txt">Table of n, a(n) for n = 1..220</a>

%H <a href="/index/Di#divseq">Index to divisibility sequences</a>

%p select(x->"6"=""||x[1],[2^n$n=0..180])[];

%t Select[2^Range[160], First[IntegerDigits[#]] == 6 &] (* _G. C. Greubel_, Oct 27 2018 *)

%o (GAP) Filtered(List([0..180],n->2^n),i->ListOfDigits(i)[1]=6);

%o (PARI) select(x->(digits(x)[1]==6), vector(200, n, 2^n)) \\ _Michel Marcus_, Oct 26 2018

%o (Magma) [2^n: n in [1..160] | Intseq(2^n)[#Intseq(2^n)] eq 6]; // _G. C. Greubel_, Oct 27 2018

%Y Cf. A000079 (powers of 2), A008952 (leading digit of 2^n), A217399 (numbers starting with 6).

%Y Powers of 2 with initial digit k, (k = 1..6): A067488, A067480, A320859, A320860, A320861, this sequence.

%K base,nonn

%O 1,1

%A _Muniru A Asiru_, Oct 23 2018