|
Search: id:A112015
|
|
|
| A112015 |
|
Numbers n with odd length such that sigma(n) = (d_1^d_2)*(d_3^d_4) *...*(d_(k-2)^d_(k-1))*d_k where d_1 d_2 ... d_k is the decimal expansion of n. |
|
+0
3
|
| |
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
There is no further term up to 10^7.
|
|
EXAMPLE
|
4461365 is in the sequence because sigma(4461365)=(4^4)*(6^1)*(3^6)*5.
|
|
MATHEMATICA
|
Do[h=IntegerDigits[n]; k=Length[h]; If[h[[k]] != 0 && OddQ[k] && Select[Range[k/2], h[[2#-1]] == 0 ==h[[2# ]] &] == {} && DivisorSigma[1, n] == h[[k]]*Product[h[[2j-1]]^h[[2j]], {j, k/2}], Print[n]], {n, 10^7}]
|
|
CROSSREFS
|
Cf. A112014, A112016.
Sequence in context: A043635 A106774 A075671 this_sequence A128879 A089009 A093791
Adjacent sequences: A112012 A112013 A112014 this_sequence A112016 A112017 A112018
|
|
KEYWORD
|
base,more,nonn
|
|
AUTHOR
|
Farideh Firoozbakht (mymontain(AT)yahoo.com), Sep 14 2005
|
|
|
Search completed in 0.002 seconds
|
