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A097446 Concatenate consecutive prime-sided isosceles triangles. 0
233, 355, 577, 71111, 111313, 131717, 171919, 192323, 232929, 293131, 313737, 374141, 414343, 434747, 475353, 535959, 596161, 616767, 677171, 717373, 737979, 798383, 838989, 899797, 97101101, 101103103, 103107107, 107109109, 109113113 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..30.

FORMULA

Consider triangles with sides (2, 3, 3), (3, 5, 5), .., (x, y, y) where x is prime and y is the next prime after x. Concatenate these sides for output.

EXAMPLE

For side x = 7, y = 11 to get concatenate 71111.

MATHEMATICA

con[a_, b_]:=FromDigits[Join[IntegerDigits[a], IntegerDigits[b], IntegerDigits[ b]]]; con@@@Partition[Prime[Range[50]], 2, 1] (* Harvey P. Dale, Jul 25 2011 *)

PROG

(PARI) f(n) = for(x=1, n, y=Str(prime(x)); y=concat(y, concat(Str(prime(x+1)), Str(prime (x+1)))); print1(y", "))

CROSSREFS

Sequence in context: A160574 A087862 A141280 * A154621 A243891 A142644

Adjacent sequences:  A097443 A097444 A097445 * A097447 A097448 A097449

KEYWORD

nonn,base

AUTHOR

Cino Hilliard, Aug 23 2004

STATUS

approved

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Last modified October 20 02:35 EDT 2019. Contains 328244 sequences. (Running on oeis4.)