A320859 Powers of 2 with initial digit 3.

32, 32768, 33554432, 34359738368, 35184372088832, 36028797018963968, 36893488147419103232, 37778931862957161709568, 302231454903657293676544, 38685626227668133590597632, 309485009821345068724781056, 39614081257132168796771975168, 316912650057057350374175801344

Offset: 1

Author

Muniru A Asiru, Oct 22 2018

Keywords

• base
• nonn

Links

• Muniru A Asiru, Table of n, a(n) for n = 1..410
• Index to divisibility sequences

Crossrefs

Cf. A000079 (Powers of 2), A008952 (leading digit of 2^n).

Powers of 2 with initial digit k, (k = 1..4): A067488, A067480, this sequence, A320860.

Cf. A172404.

Programs

GAP

Filtered(List([0..120],n->2^n),i->ListOfDigits(i)[1]=3);

Magma

[2^n: n in [1..100] | Intseq(2^n)[#Intseq(2^n)] eq 3]; // G. C. Greubel, Oct 24 2018

Maple

select(x->"3"=""||x[1],[2^n$n=0..120])[];

Mathematica

Select[2^Range[0, 100], First[IntegerDigits[#]] == 3 &] (* G. C. Greubel, Oct 24 2018 *)

PARI

lista(nn) = {for(n=1, nn, x = 2^n; if (digits(x=2^n)[1] == 3, print1(x, ", ")););} \\ Michel Marcus, Oct 25 2018

Formula

a(n) = 2^A172404(n).