id:A127937 - OEIS Search Results

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Length of longest string of consecutive zeros in the base-7 expansion of 2^n.

+0
1

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 3, 3, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 0, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1 (list; graph; listen)

	OFFSET	`0,39`
	COMMENT	`Is a(n) >= 3 for all n >= 8834?`
	EXAMPLE	`a(42)=2 because the base-7 expansion of 2^42 is 113200616214553321.`
	PROGRAM	#!/usr/bin/perl -l $\|++; use Math::GMP; use strict; my $n = new Math::GMP 1; my $pow = 0; while (1) { my $base7 = basebexpansionofn(7, $n); my $maxconsecutivezeros = 0; while ($base7 =~ /(0+)/g) { if (length($1) > $maxconsecutivezeros) { $maxconsecutivezeros = length($1); } } print "a($pow)=$maxconsecutivezeros"; $n *= 2; $pow++; } sub basebexpansionofn { my ($b, $n) = @_; return '0' if $n == 0; my $lastdigit = $n % $b; my $firstdigits = ($n - $lastdigit)/$b; return ($firstdigits ? basebexpansionofn($b, $firstdigits) : '').$lastdigit; }
	CROSSREFS	`Adjacent sequences: A127934 A127935 A127936 this_sequence A127938 A127939 A127940` `Sequence in context: A113607 A082586 A043283 this_sequence A083911 A095827 A091887`
	KEYWORD	`nonn`
	AUTHOR	`Josh Purinton (joshpurinton(AT)gmail.com), Apr 06 2007`

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Last modified October 16 00:31 EDT 2008. Contains 145098 sequences.

AT&T Labs Research