|
|
A129499
|
|
Records for unitary abundant numbers, i.e., those integers which set a record for having a greater unitary abundance than any of their predecessors.
|
|
3
|
|
|
30, 210, 330, 390, 510, 570, 690, 870, 930, 1110, 1230, 1290, 1410, 1470, 1590, 1770, 1830, 2010, 2130, 2190, 2310, 2730, 3570, 3990, 4830, 5610, 6090, 6510, 7590, 7770, 8610, 9030, 9870, 11130, 12390, 12810, 14070, 14910, 15330, 16590, 17430, 18690
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
Values of A034683 corresponding to those positions in A129498 at which records occur.
|
|
EXAMPLE
|
A129498 begins 12, 12, 12, 4, 12, 12, 12, 12, 12, 12, 12, 156, 12, 12. The second record value is 156, which occurs at position 12. As A034683(12)=210, it follows that a(2)=210.
|
|
MATHEMATICA
|
UnitaryDivisors[n_Integer?Positive]:=Select[Divisors[n], GCD[ #, n/# ]==1&]; sstar[n_]:=Plus@@UnitaryDivisors[n]-n; RunningMaxima[l_]:=Rest[FoldList[Max, -Infinity, l]] HighWaterMarks[l_]:=Module[{s=Split[RunningMaxima[l]]}, {First/@s, Most[FoldList[Plus, 1, Length/@s]]} ]; data1=Select[Range[20000], sstar[ # ]-#>0 &]; data2=sstar[ # ]-# &/@data1; pos=Last[HighWaterMarks[data2]]; champs=data1[[ # ]] &/@pos
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|