A236551 Primes formed from concatenation of PrimePi(n) and prime(n).

2, 13, 311, 313, 419, 641, 643, 647, 653, 761, 983, 997, 9103, 11131, 11149, 12157, 12163, 14197, 15227, 15233, 18307, 18311, 18313, 20353, 20359, 21379, 21383, 21397, 22409, 23431, 24499, 25523, 25541, 26557, 29599, 30631, 30643, 30661, 30677, 31727, 33773

Offset

1,1

Links

K. D. Bajpai, Table of n, a(n) for n = 1..1461

Example

pi(6) = 3: prime(6) = 13. Concatenation of 3 and 13 gives 313 which is prime and appears in the sequence.
pi(8) = 4: prime(6) = 19. Concatenation of 4 and 19 gives 419 which is prime and appears in the sequence.

Maple

with(StringTools): with(numtheory): KD := proc() local a, b, d; a:=pi(n); b:=ithprime(n); d:=parse(cat(a, b));  if isprime (d) then RETURN (d); fi;  end: seq(KD(), n=1..300);

Mathematica

Select[Table[FromDigits[Flatten[{IntegerDigits[PrimePi[n]], IntegerDigits[Prime[n]]}]], {n, 100}], PrimeQ] (* Alonso del Arte, Jan 28 2014 *)

Crossrefs

Cf. A030458 (primes: concatenation of n and n+1), A084667 (primes: concatenation of n and prime(n)), A084669 (primes: concatenation of prime(n) and n).

Sequence in context: A011841 A013106 A134485 * A304727 A355730 A075620

Adjacent sequences: A236548 A236549 A236550 * A236552 A236553 A236554

Keyword

nonn,base,less

Author

K. D. Bajpai, Jan 28 2014

Status

approved