A320860 - OEIS

%I #27 Sep 08 2022 08:46:23

%S 4,4096,4194304,4294967296,4398046511104,4503599627370496,

%T 4611686018427387904,4722366482869645213696,4835703278458516698824704,

%U 4951760157141521099596496896,40564819207303340847894502572032,41538374868278621028243970633760768

%N Powers of 2 with initial digit 4.

%C Differs from A067482 first at n = 11.

%H Muniru A Asiru, <a href="/A320860/b320860.txt">Table of n, a(n) for n = 1..320</a>

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

%p select(x->"4"=""||x[1],[2^n$n=0..150])[];

%t Select[2^Range[160], First[IntegerDigits[#]] == 4 &] (* _G. C. Greubel_, Oct 27 2018 *)

%o (GAP) Filtered(List([0..150],n->2^n),i->ListOfDigits(i)[1]=4);

%o (PARI) select(x->(digits(x)[1]==4), 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 4]; // _G. C. Greubel_, Oct 27 2018

%Y Cf. A000079 (Powers of 2), A008952 (leading digit of 2^n), A217397 (numbers starting with 4).

%Y Powers of 2 with initial digit k, (k = 1..4): A067488, A067480, A320859, this sequence.

%K base,nonn

%O 1,1

%A _Muniru A Asiru_, Oct 22 2018