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A165722
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Positive integers k such that the sum of decimal digits of (16^k - 1) equals 6*k.
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2
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1, 2, 3, 4, 5, 6, 7, 10, 12, 13, 14, 17, 18, 23, 37, 43, 46, 60, 119, 183, 223
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OFFSET
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1,2
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COMMENTS
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Conjecture: For k > 223, digsum(16^k - 1) < 6*k. This would mean that no further terms exist in the sequence. - Iain Fox, Nov 22 2017
No other terms below 10^6. - Iain Fox, Nov 25 2017
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LINKS
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EXAMPLE
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For k=1, 16-1 is 15 with sum of digits 6, so 1 is a term.
For k=2, 16^2-1 is 255 with sum of digits 12, so 2 is a term.
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MATHEMATICA
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Select[Range[250], 6#==Total[IntegerDigits[16^#-1]]&] (* Harvey P. Dale, Nov 13 2012 *)
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PROG
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(PARI) is(n) = 6*n == sumdigits(16^n-1) \\ Iain Fox, Nov 24 2017
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CROSSREFS
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KEYWORD
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base,more,nonn
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AUTHOR
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STATUS
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approved
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