The On-Line Encyclopedia of Integer Sequences (OEIS)

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A068842

Smallest prime larger than 2^n whose digits begin with those of 2^n.
(history; published version)

#6 by N. J. A. Sloane at Tue Jun 24 01:08:23 EDT 2014

EXTENSIONS

Edited by _Dean Hickerson (dean.hickerson(AT)yahoo.com), _, Jun 09 2002

Discussion

Tue Jun 24

01:08

OEIS Server: https://oeis.org/edit/global/2238

#5 by N. J. A. Sloane at Thu Dec 05 19:55:13 EST 2013

AUTHOR

_Amarnath Murthy (amarnath_murthy(AT)yahoo.com), _, Mar 10 2002

Discussion

Thu Dec 05

19:55

OEIS Server: https://oeis.org/edit/global/2075

#4 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009

KEYWORD

nonn,base,new

EXTENSIONS

Edited by Dean Hickerson (dean.hickerson(AT)math.ucdavisyahoo.educom), Jun 09 2002

#3 by N. J. A. Sloane at Fri Feb 24 03:00:00 EST 2006

MATHEMATICA

f[n_] := For[x=10, True, x*=10, For[y=0, y<x, y++, If[PrimeQ[x*n+y], Return[x*n+y]]]]; a[n_] := f[2^n]

KEYWORD

nonn,base,new

#2 by N. J. A. Sloane at Sat Jun 12 03:00:00 EDT 2004

MATHEMATICA

f[n_] := For[x=10, True, x*=10, For[y=0, y<x, y++, If[PrimeQ[x*n+y], Return[x*n+y]]]]; a[n_] := f[2^n]

KEYWORD

nonn,base,new

#1 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

NAME

Smallest prime larger than 2^n whose digits begin with those of 2^n.

DATA

11, 23, 41, 83, 163, 3203, 641, 1283, 25601, 51203, 10243, 20483, 40961, 81929, 163841, 327689, 6553621, 1310723, 2621447, 5242883, 10485767, 20971529, 41943049, 838860817, 167772161, 335544323, 6710886407, 1342177283

OFFSET

0,1

EXAMPLE

a(5) = 3203 with leading digits 32 = 2^5.

MATHEMATICA

f[n_]:=For[x=10, True, x*=10, For[y=0, y<x, y++, If[PrimeQ[x*n+y], Return[x*n+y]]]]; a[n_]:=f[2^n]

CROSSREFS

Cf. A068841.

KEYWORD

nonn,base

AUTHOR

Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 10 2002

EXTENSIONS

Edited by Dean Hickerson (dean(AT)math.ucdavis.edu), Jun 09 2002

STATUS

approved