|
| |
|
|
A134101
|
|
Odd nonprimes followed by but not preceded by primes.
|
|
4
| |
|
|
27, 35, 51, 57, 65, 77, 87, 95, 125, 135, 147, 155, 161, 171, 177, 189, 209, 221, 237, 249, 255, 261, 267, 275, 291, 305, 329, 335, 345, 357, 365, 371, 377, 387, 395, 407, 417, 429, 437, 447, 455, 477, 485, 497, 507, 519, 539, 545, 555, 561, 567, 575, 585
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
EXAMPLE
| a(1)=27 because this odd nonprime is followed by the prime 29 but preceded by the odd nonprime 25.
|
|
|
MATHEMATICA
| Select[Range[5, 1000, 2], !PrimeQ[#]&&!PrimeQ[#-2]&&PrimeQ[#+2]&] (* From Vladimir Joseph Stephan Orlovsky, Feb 03 2012 *)
|
|
|
PROG
| UBASIC: 10 'primes using counters 20 N=3:print "2 "; :print "3 "; :C=2 30 A=3:S=sqrt(N) 40 B=N\A 50 if B*A=N then 55 55 Q=N-2:R=N+2: if Q<>prmdiv(Q) and N<>prmdiv(N) and R=prmdiv(R) then print Q; N; R; "-"; :stop:else N=N+2:goto 30 60 A=A+2 70 if A<=sqrt(N) then 40:stop 81 C=C+1 100 N=N+2:goto 30
|
|
|
CROSSREFS
| Cf. A134100 A134099 A083370 A124582 A007510.
Sequence in context: A072492 A164376 A025583 * A098883 A160119 A160379
Adjacent sequences: A134098 A134099 A134100 * A134102 A134103 A134104
|
|
|
KEYWORD
| easy,nonn,changed
|
|
|
AUTHOR
| Enoch Haga (Enokh(AT)comcast.net), Oct 08 2007
|
| |
|
|
