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Search: id:A067863
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| A067863 |
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Numbers n such that n divides the sum of digits of 7^n. |
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+0
1
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OFFSET
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1,2
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COMMENT
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There are no other terms < 3000. - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Mar 14 2006
No more terms < 50000. - David Wasserman (dwasserm(AT)earthlink.net), May 30 2008
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EXAMPLE
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a(1)=13, so 13 divides sum of digits of 7^13 (i.e.9+6+8+8+9+0+1+0+4+0+7=52).
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MATHEMATICA
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For[n = 1, n < 2000, n++, a := DigitCount[7^n]; If[IntegerQ[Sum[a[[i]]*i, {i, 1, 9}]/n], Print[n]]] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Mar 14 2006
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CROSSREFS
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Cf. A062927, A067862, A067864.
Sequence in context: A041320 A058380 A129746 this_sequence A106975 A086689 A141956
Adjacent sequences: A067860 A067861 A067862 this_sequence A067864 A067865 A067866
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KEYWORD
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hard,more,nonn,base
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AUTHOR
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Shyam Sunder Gupta (guptass(AT)rediffmail.com) and Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 16 2002
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