|
|
A318993
|
|
Matula-Goebel number of the planted achiral tree determined by the n-th number whose consecutive prime indices are divisible.
|
|
4
|
|
|
1, 2, 4, 3, 8, 7, 16, 5, 9, 19, 32, 17, 64, 53, 11, 128, 23, 256, 67, 49, 131, 512, 59, 27, 311, 25, 241, 1024, 2048, 31, 719, 83, 4096, 1619, 361, 331, 8192, 227, 16384, 739, 3671, 32768, 277, 81, 103, 2063, 65536, 97, 1523, 2809, 8161, 131072, 262144, 17863
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
The sequence of all planted achiral trees begins: o, (o), (oo), ((o)), (ooo), ((oo)), (oooo), (((o))), ((o)(o)), ((ooo)), (ooooo), (((oo))), (oooooo), ((oooo)), ((((o)))), (ooooooo), (((o)(o))), (oooooooo), (((ooo))), ((oo)(oo)).
|
|
MATHEMATICA
|
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
ptnToAch[y_]:=Fold[Table[#1, {#2}]&, {}, Divide@@@Partition[Append[y, 1], 2, 1]];
MGNumber[_[]]:=1; MGNumber[x:_[__]]:=If[Length[x]==1, Prime[MGNumber[x[[1]]]], Times@@Prime/@MGNumber/@x];
MGNumber/@ptnToAch/@Reverse/@primeMS/@Select[Range[100], Or[#==1, PrimeQ[#], Divisible@@Reverse[primeMS[#]]]&]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|