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 A235649 Define a(4)=3 then a(n+1)is the smallest prime P such that a(n)<=P< n with 2*n-P=Q prime and if not possible a(n+1) is the smallest prime P such that P
 3, 3, 5, 3, 3, 5, 7, 3, 5, 7, 11, 11, 13, 3, 5, 7, 11, 11, 13, 17, 17, 19, 23, 23, 3, 5, 7, 19, 23, 23, 31, 3, 5, 7, 17, 17, 19, 23, 23, 3, 5, 7, 13, 23, 23, 31, 41, 41, 43, 47, 47, 3, 3, 5, 7, 11, 11, 13, 17, 17, 19, 23, 23, 31, 47, 59, 61, 3, 5, 7, 11 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,1 LINKS Pierre CAMI, Table of n, a(n) for n = 4..10005 EXAMPLE a(4)=3 as 2*4-3=5 prime by definition a(5)=3 as 2*5-3=7 prime, a(5)=a(4), a(5)<5 a(6)=5 as 2*6-5=7 prime, a(6)>a(5), a(6)<6 a(7)=5 not possible as 14-5=9 composite a(7)=7 not possible as 7=7 a(7)=3 as 2*7-3=11 prime a(8)=3 as 2*8-3=13 prime PROG (PFGW & SCRIPT) SCRIPT DIM n, 3 DIM i DIM pp DIMS t OPENFILEOUT myf, a(n).txt LABEL loop1 OPENFILEIN maf, prime.txt GETNEXT i, maf GETNEXT i, maf LABEL a SET n, n+1 IF n>10005 THEN END SET pp, 2*n-i SETS t, %d, %d\,; n; i PRP pp, t IF ISPRP THEN GOTO c LABEL b GETNEXT i, maf IF n-i<3 THEN GOTO d SET pp, 2*n-i SETS t, %d, %d\,; n; i PRP pp, t IF ISPRP THEN GOTO c GOTO b LABEL c WRITE myf, t GOTO a LABEL d CLOSEFILE maf SET n, n-1 GOTO loop1 CROSSREFS Cf. A002373, A020483 Sequence in context: A136019 A242017 A063714 * A113965 A162277 A365512 Adjacent sequences: A235646 A235647 A235648 * A235650 A235651 A235652 KEYWORD nonn AUTHOR Pierre CAMI, Jan 13 2014 STATUS approved

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Last modified September 30 04:40 EDT 2023. Contains 365781 sequences. (Running on oeis4.)