|
Search: id:A067847
|
|
|
| A067847 |
|
Number of divisors d of n! such that d+1 is prime. |
|
+0
2
|
|
| 1, 2, 3, 5, 9, 15, 27, 40, 63, 100, 180, 248, 459, 696, 1019, 1299, 2495, 3219, 6011, 7986, 11247, 17029, 32567, 39501, 53017, 79775, 97251, 118584
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
EXAMPLE
|
a(5)=9 because the divisors of 5!=120 are 1,2,3,4,5,6,8,10,12,15,20,24,30,60 and 120 and the prime are 2,3,5,7,11,13,31,41 and 61
|
|
PROGRAM
|
(PARI) a(n)=s=0; fordiv (n!, i, if(isprime(n!/i+1), s=s+1)); return(s);
|
|
CROSSREFS
|
Cf. A067513.
Sequence in context: A005169 A129852 A065954 this_sequence A022858 A090905 A065956
Adjacent sequences: A067844 A067845 A067846 this_sequence A067848 A067849 A067850
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladeta Jovovic (vladeta(AT)Eunet.yu), Feb 14 2002
|
|
EXTENSIONS
|
More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Mar 19 2002
More terms from Naohiro Nomoto (n_nomoto(AT)yabumi.com), Mar 13 2002
More terms from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 26 2004
118584 from Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 07 2004
|
|
|
Search completed in 0.002 seconds
|
