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URL: https://oeis.org/A048447

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A048447
Take the first n numbers written in base 16, concatenate them, then convert from base 16 to base 10.
18
1, 18, 291, 4660, 74565, 1193046, 19088743, 305419896, 4886718345, 78187493530, 1250999896491, 20015998343868, 320255973501901, 5124095576030430, 81985529216486895, 20988295479420645136, 5373003642731685154833, 1375488932539311399637266, 352125166730063718307140115
OFFSET
1,2
LINKS
EXAMPLE
a(16) = (1)(2)(3)(4)(5)(6)(7)(8)(9)(A)(B)(C)(D)(E)(F)(10) = 123456789ABCDEF10_16 = 20988295479420645136.
MATHEMATICA
If[STARTPOINT==1, n={}, n=Flatten[IntegerDigits[Range[STARTPOINT-1], 16]]]; Table[AppendTo[n, IntegerDigits[w, 16]]; n=Flatten[n]; FromDigits[n, 16], {w, STARTPOINT, ENDPOINT}] (* Dylan Hamilton, Aug 11 2010 *)
f[n_]:= FromDigits[Flatten@IntegerDigits[Range@n, 16], 16]; Array[f, 20] (* Vincenzo Librandi, Dec 30 2012 *)
PROG
(Magma) [n eq 1 select 1 else Self(n-1)*16^(1+Ilog(16, n))+n: n in [1..20]]; // Vincenzo Librandi, Dec 30 2012
(Python)
from functools import reduce
def A048447(n): return reduce(lambda i, j:(i<<(bool((m:=j.bit_length())&3)<<2)+(m&-4))+j, range(n+1)) # Chai Wah Wu, Feb 26 2023
CROSSREFS
Cf. A014899.
Concatenation of first n numbers in other bases: 2: A047778, 3: A048435, 4: A048436, 5: A048437, 6: A048438, 7: A048439, 8: A048440, 9: A048441, 10: A007908, 11: A048442, 12: A048443, 13: A048444, 14: A048445, 15: A048446, 16: this sequence.
Sequence in context: A232154 A386615 A014899 * A167713 A219670 A383172
KEYWORD
nonn,base,easy
AUTHOR
Patrick De Geest, May 15 1999
STATUS
approved