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A112016
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.
3
1, 127, 1443572, 2859151, 5272635, 5469390, 5668072, 9662421, 121734535, 124825592, 161367245, 168215370, 185335291, 211254594, 217299630, 225624553, 236125265, 251716960, 271374710, 272433643, 291732835, 292536521, 345267332
OFFSET
1,2
EXAMPLE
161367245 is in the sequence because sigma(161367245)=1*(6^1)*(3^6)*(7^2)*(4^5).
MATHEMATICA
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}]
CROSSREFS
Sequence in context: A212860 A334668 A135813 * A263165 A135982 A135983
KEYWORD
base,nonn
AUTHOR
Farideh Firoozbakht, Sep 15 2005
EXTENSIONS
a(11)-a(23) from Donovan Johnson, Sep 16 2009
STATUS
approved