|
| |
|
|
A080393
|
|
a(n) is the smallest integer such that A080383(a[n])=n.
|
|
0
| |
|
|
0, 1, 2, 3, 40, 5, 12, 25, 1122, 13, 420, 1103
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,3
|
|
|
COMMENTS
| It is undecided whether all positive integers arise here or not.
|
|
|
EXAMPLE
| a(1)=0; parity of n and a(n) is opposite; n=10: a(10)=13 because in A080383 10 appears first as 13th term; extension: a(14)=421
|
|
|
MATHEMATICA
| f[x_] := Count[Table[IntegerQ[Binomial[x, Floor[x/2]]/ Binomial[x, j]], {j, 0, n}], True]; t=Table[0, {20}]; Do[s=f[n]; If[s<21&&t[[s]]==0, t[[s]]=n], {n, 1, 1300}]; t
|
|
|
CROSSREFS
| Cf. A080383, A080385(1)=a(7), A080386(1)=a(8), A080387(1)=a(10), A080384(1)=a(6).
Sequence in context: A039820 A153745 A076724 * A111683 A088984 A097170
Adjacent sequences: A080390 A080391 A080392 * A080394 A080395 A080396
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Mar 17 2003
|
| |
|
|
