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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..23.

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

Cf. A112014, A112015.

Sequence in context: A212860 A334668 A135813 * A263165 A135982 A135983

Adjacent sequences:  A112013 A112014 A112015 * A112017 A112018 A112019

KEYWORD

base,nonn

AUTHOR

Farideh Firoozbakht, Sep 15 2005

EXTENSIONS

a(11)-a(23) from Donovan Johnson, Sep 16 2009

STATUS

approved

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Last modified January 28 00:29 EST 2022. Contains 350654 sequences. (Running on oeis4.)