id:A134101 - OEIS Search Results

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Odd nonprimes followed by but not preceded by primes.

+0
5

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; listen)

	OFFSET	`1,1`
	EXAMPLE	`a(1)=27 because this odd nonprime is followed by the prime 29 but preceded by the odd nonprime 25.`
	PROGRAM	`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 this_sequence A098883 A160119 A160379` `Adjacent sequences: A134098 A134099 A134100 this_sequence A134102 A134103 A134104`
	KEYWORD	`easy,nonn`
	AUTHOR	`Enoch Haga (Enokh(AT)comcast.net), Oct 08 2007`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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