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A211072
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Sum of numbers with no '0' decimal digits whose sum of digits equals n.
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5
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0, 1, 13, 147, 1625, 17891, 196833, 2165227, 23817625, 261994131, 2881935943, 31701296375, 348714262017, 3835856884757, 42194425724149, 464138682802857, 5105525508895321, 56160780576260645, 617768586100819485, 6795454444489330049, 74749998860563784655
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OFFSET
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0,3
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COMMENTS
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (11,1,-9,-19,-29,-39,-49,-59,-69,-90,-80,-70,-60,-50,-40,-30,-20,-10).
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FORMULA
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G.f.: x*(9*x^8 + 8*x^7 + 7*x^6 + 6*x^5 + 5*x^4 + 4*x^3 + 3*x^2 + 2*x + 1)/((x^9 + x^8 + x^7 + x^6 + x^5 + x^4 + x^3 + x^2 + x - 1)*(10*x^9 + 10*x^8 + 10*x^7 + 10*x^6 + 10*x^5 + 10*x^4 + 10*x^3 + 10*x^2 + 10*x - 1)). - Yurii Ivanov, Jul 06 2021
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EXAMPLE
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2 and 11 are the only numbers without 0's which have digit sum 2, so a(2) = 2 + 11 = 13.
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MAPLE
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b:= proc(n) option remember; `if`(n=0, [1, 0], add((p->
[p[1], p[2]*10+p[1]*d])(b(n-d)), d=1..min(n, 9)))
end:
a:= n-> b(n)[2]:
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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