A154531 Primes that are a concatenation of consecutive primes in two ways.
199211, 211199, 233239, 239233, 257263, 263257, 353359, 359353, 523541, 541523, 653659, 659653, 971977, 977971, 19731979, 19791973, 23332339, 23392333, 32593271, 32713259, 36373643, 36433637, 37613767, 37673761, 42834289, 42894283, 49934999, 49994993
Offset: 1
Examples
233 and 239 consecutive primes, 233239 and 239233 are both primes.
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
ccp2[{a_,b_}]:=Module[{c=a*10^IntegerLength[b]+b,d=b*10^IntegerLength[a]+ a}, If[ AllTrue[ {c,d}, PrimeQ],{c,d},{}]]; ccp2/@Partition[Prime[ Range[ 1000]],2,1]//Flatten (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 20 2017 *)
Extensions
Corrected by Harvey P. Dale, Feb 20 2017