login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A045532
Concatenate n with n-th prime.
14
12, 23, 35, 47, 511, 613, 717, 819, 923, 1029, 1131, 1237, 1341, 1443, 1547, 1653, 1759, 1861, 1967, 2071, 2173, 2279, 2383, 2489, 2597, 26101, 27103, 28107, 29109, 30113, 31127, 32131, 33137, 34139, 35149, 36151, 37157, 38163, 39167, 40173, 41179, 42181
OFFSET
1,1
COMMENTS
Triangular numbers are 1653, 32131, 79401, ... - Ali Adams, Feb 04 2020
The next such terms are 173340627863131 and 1454987833022905581. - Giovanni Resta, Feb 04 2020
LINKS
FORMULA
a(n) = n*10^(A004216(A000040(n))+1) + A000040(n). - Reinhard Zumkeller, Sep 03 2002
MATHEMATICA
Table[FromDigits[Join[IntegerDigits[n], IntegerDigits[Prime[n]]]], {n, 40}] (* Vincenzo Librandi, Apr 13 2019 *)
#[[1]]*10^IntegerLength[#[[2]]]+#[[2]]&/@Table[{n, Prime[n]}, {n, 50}] (* Harvey P. Dale, Oct 11 2024 *)
PROG
(Haskell)
a045532 n = read $ show n ++ show (a000040 n) :: Integer
-- Reinhard Zumkeller, Jul 08 2014
(Magma) [Seqint(Intseq(NthPrime(n)) cat Intseq(n)): n in [1..45]]; // Vincenzo Librandi, Apr 13 2019
(PARI) a(n) = eval(Str(n, prime(n))); \\ Michel Marcus, Apr 13 2019, simplified by M. F. Hasler, Feb 05 2020
(Python)
from sympy import prime
def a(n): return int(str(n) + str(prime(n)))
print([a(n) for n in range(1, 43)]) # Michael S. Branicky, Dec 23 2021
CROSSREFS
Cf. A085451. [Reinhard Zumkeller, Jun 30 2010]
Sequence in context: A233032 A088997 A049852 * A255729 A341740 A190426
KEYWORD
nonn,base
AUTHOR
STATUS
approved