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A271422
Concatenation of prime(n) and its square.
0
24, 39, 525, 749, 11121, 13169, 17289, 19361, 23529, 29841, 31961, 371369, 411681, 431849, 472209, 532809, 593481, 613721, 674489, 715041, 735329, 796241, 836889, 897921, 979409, 10110201, 10310609, 10711449, 10911881, 11312769, 12716129, 13117161, 13718769
OFFSET
1,1
COMMENTS
All concatenations are divisible by the n-th prime.
a(n)/prime(n) gives a number of the form concatenate[(10^k)_prime(n)] for some k.
Subsequence of A053061.
Except for 24 and 525, a(n) have final decimal digit 1 or 9.
FORMULA
a(n) = Concatenate [prime(n)_A001248(n)].
a(n) = p*(p+10^A055642(p^2)) with p = prime(n). - Peter Luschny, Jul 17 2016
EXAMPLE
For n=4, prime(4) = 7 (the fourth prime number) and 7^2 = 49. These are concatenated to get a(4) = 749. - Michael B. Porter, Jul 16 2016
MAPLE
seq(n*(n+10^(1+ilog10(n^2))), n=select(k->isprime(k), [$1..137])); # Peter Luschny, Jul 16 2016
MATHEMATICA
Table[FromDigits@ Flatten@ Map[IntegerDigits, {#, #^2}] &@ Prime@ n, {n, 33}] (* Michael De Vlieger, Jul 13 2016 *)
PROG
(PARI) a(n) = eval(Str(prime(n), prime(n)^2)) \\ Felix Fröhlich, Jul 14 2016
CROSSREFS
Cf. A001248 (primes squared), A030078 (primes cubed), A053061, A038800, (number of primes between 10n and 10n+9.
Sequence in context: A047982 A210456 A095158 * A362148 A062374 A272593
KEYWORD
nonn,easy,base
AUTHOR
Giovanni Teofilatto, Jul 13 2016
STATUS
approved