A320863 Powers of 2 with initial digit 7.

70368744177664, 72057594037927936, 73786976294838206464, 75557863725914323419136, 77371252455336267181195264, 79228162514264337593543950336, 713623846352979940529142984724747568191373312, 730750818665451459101842416358141509827966271488

Offset: 1

Author

Muniru A Asiru, Oct 26 2018

Keywords

• base
• nonn

Links

• Muniru A Asiru, Table of n, a(n) for n = 1..170
• Index to divisibility sequences

Crossrefs

Cf. A000079 (powers of 2), A008952 (leading digit of 2^n), A217400 (numbers starting with 7).

Powers of 2 with initial digit k, (k = 1..7): A067488, A067480, A320859, A320860, A320861, A320862, this sequence.

Programs

GAP

Filtered(List([0..180],n->2^n),i->ListOfDigits(i)[1]=7);

Magma

[2^n: n in [1..160] | Intseq(2^n)[#Intseq(2^n)] eq 7]; // G. C. Greubel, Oct 27 2018

Maple

select(x->"7"=""||x[1],[2^n$n=0..180])[];

Mathematica

Select[2^Range[160], First[IntegerDigits[#]] == 7 &] (* G. C. Greubel, Oct 27 2018 *)

PARI

select(x->(digits(x)[1]==7), vector(200, n, 2^n)) \\ Michel Marcus, Oct 27 2018