|
Search: id:A081475
|
|
|
| A081475 |
|
Consider the mapping f(a/b) = (a + b)/(2ab). Taking a = 1 b = 2 to start with, and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 1/2,3/2,5/12,17/,137/4080,... Sequence contains the numerators. |
|
+0
2
|
|
| 1, 3, 7, 31, 367, 21199, 15311887, 648309901711, 19853227652502777487, 25742087295488761786102488482959, 1022127038655087543344600484892552190865956757100687
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
An infinite coprime sequence defined by recursion.
Every term is relatively prime to all others. - Michael Somos Feb 01 2004
|
|
PROGRAM
|
(PARI) a(n)=local(v); if(n<2, n>0, v=[1, 2]; for(k=2, n, v=[v[1]+v[2], 2*v[1]*v[2]]); v[1])
|
|
CROSSREFS
|
Cf. A001685, A003686, A064526. The denominators are A081476.
Adjacent sequences: A081472 A081473 A081474 this_sequence A081476 A081477 A081478
Sequence in context: A063896 A074047 A121810 this_sequence A123212 A070231 A096239
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 24 2003
|
|
EXTENSIONS
|
Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003
|
|
|
Search completed in 0.006 seconds
|
