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 A127937 Length of longest string of consecutive zeros in the base-7 expansion of 2^n. 0
 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; refs; listen; history; text; internal format)
 OFFSET 0,39 COMMENTS Is a(n) >= 3 for all n >= 8834? LINKS EXAMPLE a(42)=2 because the base-7 expansion of 2^42 is 113200616214553321. PROG #!/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 Sequence in context: A082586 A160094 A043283 * A250209 A280010 A167852 Adjacent sequences:  A127934 A127935 A127936 * A127938 A127939 A127940 KEYWORD nonn AUTHOR Josh Purinton (joshpurinton(AT)gmail.com), Apr 06 2007 STATUS approved

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Last modified November 24 00:27 EST 2017. Contains 295164 sequences.