A067480 Powers of 2 with initial digit 2.

2, 256, 2048, 262144, 2097152, 268435456, 2147483648, 274877906944, 2199023255552, 281474976710656, 2251799813685248, 288230376151711744, 2305843009213693952, 295147905179352825856, 2361183241434822606848, 2417851639229258349412352, 2475880078570760549798248448

Offset: 1

Author

Amarnath Murthy, Feb 09 2002

Keywords

• base
• easy
• nonn

Links

• Muniru A Asiru, Table of n, a(n) for n = 1..400

Crossrefs

Cf. A000079, A067469, A067483.

Programs

GAP

k:=2;; Filtered(List([0..100],n->k^n),i->ListOfDigits(i)[1]=k); # Muniru A Asiru, Oct 19 2018

Magma

[2^n: n in [1..100] | Intseq(2^n)[#Intseq(2^n)] eq 2]; // Vincenzo Librandi, Oct 22 2018

Mathematica

Select[Table[2^n,{n,75}],First@IntegerDigits[#]==2 &] (* Jayanta Basu, May 19 2013 *)
Select[2^Range[100], First[IntegerDigits[#]]==2 &] (* Vincenzo Librandi, Oct 22 2018 *)

PARI

lista(nn) = {for (n=0, nn, if (digits(x=2^n)[1] == 2, print1(x, ", ")););} \\ Michel Marcus, Oct 20 2018