A176316 - OEIS

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A176316

Primes p with property that concatenation prime(1)//p//prime(2) = 2//p//3 is a prime.

2, 3, 11, 29, 47, 59, 71, 83, 101, 131, 149, 167, 227, 257, 317, 347, 359, 383, 389, 479, 503, 563, 569, 587, 593, 683, 773, 839, 857, 881, 947, 983, 1019, 1091, 1109, 1187, 1193, 1229, 1259, 1319, 1361, 1499, 1583, 1613, 1637, 1697, 1733, 1823, 1913, 1931

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OFFSET

1,1

COMMENTS

Necessarily for p > 3: p = 6 * m + 5, as for q = 6*m+1 sod(2//q//3) is a multiple of 3

REFERENCES

E. I. Ignatjew, Mathematische Spielereien, Urania Verlag Leipzig/Jena/Berlin 1982

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

223 = prime(48), 2 = prime(1) is first term

233 = prime(51), 3 = prime(2) is 2nd term

2//05//3 = 2053 = prime(310), a "leading" zero is included, no term of sequence

2113 = prime(319), 11 = prime(5) is 3rd term

MAPLE

filter:= p -> isprime(p) and isprime(10*p+3+2*10^(2+ilog10(p))):

select(filter, [2, 3, seq(i, i=5..2000, 6)]); # Robert Israel, Nov 29 2017

CROSSREFS

Sequence in context: A335364 A235474 A075641 * A181956 A237038 A309755

Adjacent sequences: A176313 A176314 A176315 * A176317 A176318 A176319

KEYWORD

base,nonn

AUTHOR

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Apr 15 2010

STATUS

approved