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A063163 Composite numbers which in base 7 contain their largest proper factor as a substring. 0
49, 77, 91, 119, 133, 161, 203, 217, 259, 287, 301, 329, 343, 371, 413, 427, 469, 497, 511, 539, 551, 553, 581, 623, 637, 679, 707, 721, 749, 763, 791, 833, 847, 889, 917, 931, 959, 973, 989, 1001, 1043, 1057, 1099, 1127, 1141, 1169, 1183, 1211, 1253 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..49.

MATHEMATICA

Do[ If[ !PrimeQ[ n ] && StringPosition[ ToString[ FromDigits[ IntegerDigits[ n, 7 ] ] ], ToString[ FromDigits[ IntegerDigits[ Divisors[ n ] [ [ -2 ] ], 7 ] ] ] ] != {}, Print[ n ] ], {n, 2, 2000} ]

CROSSREFS

Cf. A062238.

Sequence in context: A112057 A260571 A038510 * A103216 A036307 A294028

Adjacent sequences:  A063160 A063161 A063162 * A063164 A063165 A063166

KEYWORD

base,nonn

AUTHOR

Robert G. Wilson v, Aug 08 2001

STATUS

approved

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Last modified August 12 11:29 EDT 2020. Contains 336438 sequences. (Running on oeis4.)