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Search: id:A112016
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| A112016 |
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Numbers n with odd length such that sigma(n) = d_1*(d_2^d_3) *...*(d_(k-1)^d_k) where d_1 d_2 ... d_k is the decimal expansion of n. |
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+0
4
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| 1, 127, 1443572, 2859151, 5272635, 5469390, 5668072, 9662421, 121734535, 124825592, 161367245, 168215370, 185335291, 211254594, 217299630, 225624553, 236125265, 251716960, 271374710, 272433643, 291732835, 292536521, 345267332
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OFFSET
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1,2
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EXAMPLE
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161367245 is in the sequence because sigma(161367245)=1*(6^1)*(3^6)*(7^2)*(4^5).
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MATHEMATICA
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Do[h = IntegerDigits[n]; k = Length[h]; If[OddQ[k] && Select[Range[k/2], h[[2# ]] == 0 ==h[[2#+1]] &] == {}&& DivisorSigma[1, n] == h[[1]]*Product[h[[2j]]^h[[2j+1]], {j, k/2}], Print[n]], {n, 162000000}]
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CROSSREFS
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Cf. A112014, A112015.
Sequence in context: A069408 A069434 A135813 this_sequence A135982 A135983 A101327
Adjacent sequences: A112013 A112014 A112015 this_sequence A112017 A112018 A112019
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KEYWORD
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base,nonn
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Sep 15 2005
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EXTENSIONS
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a(11)-a(23) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 16 2009
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