|
| |
|
|
A129619
|
|
a(n) = largest proper divisor of the sum of all positive integers which are <= n and are not included among the first n-1 terms of the sequence.
|
|
0
| |
|
|
1, 1, 1, 3, 1, 1, 12, 16, 1, 17, 31, 31, 25, 1, 52, 52, 52, 61, 47, 23, 91, 102, 102, 114, 114, 127, 1, 103, 169, 184, 184, 200, 1, 1, 251, 269, 115, 1, 326, 346, 1, 155, 409, 431, 1, 1, 1, 143, 525, 550, 1, 1, 602, 629, 101, 37, 463, 1, 753, 783, 783, 814, 89, 585, 910, 943
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,4
|
|
|
EXAMPLE
| The positive integers which are <= 8 and do not occur among the first 7 terms of the sequence are 2,4,5,6,7,8. a(8) is the largest proper divisor of the sum of these integers. 2+4+5+6+7+8 = 32. So a(8) is the largest proper divisor of 32, which is 16.
|
|
|
MATHEMATICA
| a = {1}; For[n = 2, n < 70, n++, AppendTo[a, Divisors[n*(n + 1)/2 - Plus @@ Select[Union[a, a], # < n + 1 &]][[ -2]]]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 21 2007
|
|
|
CROSSREFS
| Sequence in context: A078122 A128592 A156584 * A094573 A055154 A015112
Adjacent sequences: A129616 A129617 A129618 * A129620 A129621 A129622
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Leroy Quet May 30 2007
|
|
|
EXTENSIONS
| More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 21 2007
|
| |
|
|
