|
| |
|
|
A157137
|
|
Odd composite numbers n with equal number of prime digits in n and n-th prime.
|
|
0
| |
|
|
15, 33, 39, 45, 75, 81, 85, 93, 115, 117, 123, 133, 141, 145, 169, 183, 185, 187, 195, 205, 207, 209, 213, 231, 243, 247, 259, 261, 273, 275, 287, 289, 295, 299, 301, 315, 321, 325, 333, 335, 339, 343, 363, 365, 385, 387, 391, 395, 427, 477, 505, 517, 527
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Prime digits are 2, 3, 5 or 7.
|
|
|
EXAMPLE
| If prime(n=15=odd composite number)=47 and 1(5=prime)=1(7=prime), then 15=a(1). If prime(n=33=odd cohposite number)=137 and 2(3=prime and 3=prime)=2(3=prime and 7=prime), then 33=a(2). If prime(n=39=odd composite number)=167 and 1(3=prime)=1(7=prime), then 39=a(3), etc.
|
|
|
CROSSREFS
| Cf. A000027, A000040, A155548.
Sequence in context: A068081 A089967 A064900 * A141230 A140608 A085371
Adjacent sequences: A157134 A157135 A157136 * A157138 A157139 A157140
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)ramblerr), Feb 24 2009
|
|
|
EXTENSIONS
| Corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 26 2009
|
| |
|
|
