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A062885
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Smallest multiple of n with property that digits are even and each digit is two less (mod 10) than the previous digit, if such a multiple exists; otherwise -1.
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3
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0, 2, 2, 6, 4, 20, 6, 42, 8, 864, 20, 42086, 420, 208, 42, 420, 64, 8642086, 864, 642086, 20, 42, 42086, 6420864, 864, -1, 208, 864, 420, 8642, 420, 86420864208642, 64, 420864208642086, 8642086, 420, 864, 86420864208642, 642086, 86420864208642086420864208642, -1, 642086420864208642, 42, 86, 2086420864, 6420864208642086420, 6420864, 2086420864208642086, 864, 208642, -1, 864208642086420864208642086420864
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Index entries for sequences related to final digits of numbers
Don Reble, Analysis of this sequence
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EXAMPLE
| a(7) = 42 = 7*6 has decreasing even digits.
For n = 25, the conditions require that the desired multiple 25k have k even, i.e. 25k = 25(2i) = 50i = (5i)(10). Thus the final digit is 0, so the next-to-last digit must be 2, but this is impossible since 5i always ends in 0 or 5. Thus a(25) = -1. - John W. Layman (layman(AT)math.vt.edu), Nov 01 2001
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CROSSREFS
| Cf. A062884.
Sequence in context: A067045 A083467 A061807 * A062293 A204991 A054516
Adjacent sequences: A062882 A062883 A062884 * A062886 A062887 A062888
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KEYWORD
| base,easy,nice,sign
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jun 28 2001
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EXTENSIONS
| More terms and better description from John W. Layman (layman(AT)math.vt.edu), Nov 01 2001
Further terms from Jud McCranie, Nov 01, 2001
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