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A131700
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Sum of all n-digit Cullen numbers.
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0
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13, 90, 1443, 6658, 81923, 827395, 17956868, 157286403, 1434451971, 12884901891, 114353504259, 1005022347267, 8761733283843, 166026255794180, 1337006139375619, 11434920928870403, 97390341941886979, 1799188051134513156, 14231374822490767363, 119903836479112085507
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listen;
history;
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internal format)
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OFFSET
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1,1
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LINKS
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EXAMPLE
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Sum of all 1-digit Cullen numbers is 1 + 3 + 9 = 13.
Sum of all 2-digit Cullen numbers is 25 + 65 = 90.
Sum of all 3-digit Cullen numbers is 161 + 385 + 897 = 1443.
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MATHEMATICA
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digNum[n_] := Length @ IntegerDigits[n]; cullen[n_] := n * 2^n + 1; digCount = 0; sum = 0; cumsum = {}; Do[c = cullen[n]; If[digNum[c] > digCount, digCount++; AppendTo[cumsum, sum]]; sum += c, {n, 0, 65}]; Differences[cumsum] (* Amiram Eldar, Nov 30 2019 *)
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CROSSREFS
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KEYWORD
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nonn,base,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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