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A048439 Concatenation of first n numbers in base 7. 16
1, 9, 66, 466, 3267, 22875, 1120882, 54923226, 2691238083, 131870666077, 6461662637784, 316621469251428, 15514451993319985, 760208147672679279, 37250199235961284686, 1825259762562102949630, 89437728365543044531887 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The first two primes in this sequence occur for n = 10 (N = 131870666077); n = 37 (N = 569432644200356239518976257368822195317881440478377541397) (email from Kurt Foster, Oct 24 2015). What is the next prime? - N. J. A. Sloane, Oct 25 2015

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

EXAMPLE

a(8) = 1 2 3 4 5 6 10 11 = 54923226

MATHEMATICA

If[STARTPOINT==1, n={}, n=Flatten[IntegerDigits[Range[STARTPOINT-1], 7]]]; Table[AppendTo[n, IntegerDigits[w, 7]]; n=Flatten[n]; FromDigits[n, 7], {w, STARTPOINT, ENDPOINT}] [Dylan Hamilton, Aug 11 2010]

f[n_]:= FromDigits[Flatten@IntegerDigits[Range@n, 7], 7]; Array[f, 20] (* Vincenzo Librandi, Dec 30 2012 *)

PROG

(MAGMA) [n eq 1 select 1 else Self(n-1)*7^(1+Ilog(7, n))+n: n in [1..20]]; // Vincenzo Librandi, Dec 30 2012

CROSSREFS

Cf. A014830.

Concatenation of first n numbers in other bases: 2: A047778, 3: A048435, 4: A048436, 5: A048437, 6: A048438, 7: this sequence, 8: A048440, 9: A048441, 10: A007908, 11: A048442, 12: A048443, 13: A048444, 14: A048445, 15: A048446, 16: A048447.

Sequence in context: A037607 A055148 A014830 * A134432 A098107 A226201

Adjacent sequences:  A048436 A048437 A048438 * A048440 A048441 A048442

KEYWORD

nonn,base,easy

AUTHOR

Patrick De Geest, May 15 1999.

STATUS

approved

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Last modified July 21 17:51 EDT 2017. Contains 289643 sequences.