|
| |
|
|
A156343
|
|
Primes with equal number of prime and nonprime digits.
|
|
0
| |
|
|
13, 17, 29, 31, 43, 47, 59, 67, 71, 79, 83, 97, 1033, 1123, 1153, 1213, 1217, 1229, 1231, 1259, 1279, 1283, 1297, 1303, 1307, 1321, 1367, 1423, 1427, 1433, 1453, 1531, 1543, 1559, 1567, 1571, 1579, 1583, 1597, 1627, 1637, 1657, 1721, 1747, 1759, 1783, 1787
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Prime digits are 2, 3, 5 or 7. Nonprime digits are 0, 1, 4, 6, 8 or 9.
Complement of (A154385 U A154386). [Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 29 2009]
|
|
|
EXAMPLE
| 13(1=nonprime and 3=prime)=a(1).
|
|
|
MAPLE
| A109066c := proc(n) nops(convert(n, base, 10))-A109066(n) ; end:
A109066 := proc(n) local dgs, a ; dgs := convert(n, base, 10) ; a := 0 ; for i in dgs do if isprime(i) then a := a+1 ; fi; od: a ; end:
for i from 1 to 400 do p := ithprime(i) ; if A109066(p) = A109066c(p) then printf("%d, ", p) ; fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 09 2009]
|
|
|
CROSSREFS
| Cf. A000040.
Sequence in context: A179909 A152427 A092626 * A154762 A079348 A174024
Adjacent sequences: A156340 A156341 A156342 * A156344 A156345 A156346
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Feb 08 2009
|
| |
|
|
