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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

%I #5 Mar 30 2012 17:37:43

%S 1,127,1443572,2859151,5272635,5469390,5668072,9662421,121734535,

%T 124825592,161367245,168215370,185335291,211254594,217299630,

%U 225624553,236125265,251716960,271374710,272433643,291732835,292536521,345267332

%N 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.

%e 161367245 is in the sequence because sigma(161367245)=1*(6^1)*(3^6)*(7^2)*(4^5).

%t 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}]

%Y Cf. A112014, A112015.

%K base,nonn

%O 1,2

%A _Farideh Firoozbakht_, Sep 15 2005

%E a(11)-a(23) from _Donovan Johnson_, Sep 16 2009

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Last modified April 25 01:06 EDT 2024. Contains 371964 sequences. (Running on oeis4.)