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 A309934 Primes p such that p+2, (p+1)||p and (p+1)||(p+2) are primes (where || denotes concatenation in base 10). 1
 41, 101, 107, 179, 191, 269, 311, 419, 521, 659, 821, 881, 1229, 1481, 4241, 4787, 8819, 10331, 11549, 13691, 14549, 14561, 14867, 15731, 17909, 18521, 20549, 21647, 22619, 23669, 23831, 26261, 27737, 35837, 38921, 39041, 40127, 42017, 43961, 44531, 46439, 47711, 48119, 48821 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE a(3)=107 is in the sequence because 107, 109, 108107 and 108109 are primes. MAPLE Res:= {}: for d from 1 to 6 do   P:= select(isprime, {seq(i, i=10^(d-1)+1..10^d, 2)});   T:= P intersect map(`-`, P, 2);   Res:= Res union select(p -> isprime((10^d+1)*p+10^d) and isprime((10^d+1)*p+10^d+2), T); od: sort(convert(Res, list)); PROG (MAGMA) [p:p in PrimesUpTo(2200)|IsPrime(p+2) and IsPrime(Seqint(Intseq(p) cat Intseq(p+1))) and IsPrime(Seqint(Intseq(p+2) cat Intseq(p+1)))]; // Marius A. Burtea, Aug 23 2019 (PARI) isok(k) = isprime(k) && isprime(k+2) && isprime(eval(Str(k+1, k))) && isprime(eval(Str(k+1, k+2))); \\ Jinyuan Wang, Aug 26 2019 CROSSREFS Cf. A001359, A309935. Sequence in context: A142658 A228573 A273363 * A126588 A142794 A225888 Adjacent sequences:  A309931 A309932 A309933 * A309935 A309936 A309937 KEYWORD nonn,base AUTHOR J. M. Bergot and Robert Israel, Aug 23 2019 STATUS approved

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Last modified January 18 05:18 EST 2021. Contains 340250 sequences. (Running on oeis4.)