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A050923 a(n) = 2^(n!). 11
2, 2, 4, 64, 16777216, 1329227995784915872903807060280344576 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

For n > 0, every n-fold repetition of a(n) is a "powerful" arithmetic progression with difference 0; e.g., for n = 4 we get a(4) = 16777216 and in the generated repeating sequence of length 4 the k-th term is a k-th power (1 <= k <= n): 16777216 = 16777216^1, 16777216 = 4096^2, 16777216 = 256^3, 16777216 = 64^4. - Martin Renner, Aug 16 2017

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..6

Index to divisibility sequences

FORMULA

a(n) = a(n-1)^n, a(0)=2.

a(n) = A000079(A000142(n)).

MATHEMATICA

a=2; lst={}; Do[a=a^n; AppendTo[lst, a], {n, 1, 7}]; lst (* Vladimir Joseph Stephan Orlovsky, May 26 2009 *)

Table[2^n!, {n, 0, 9}] (* Vincenzo Librandi, Dec 16 2012 *)

PROG

(MAGMA) [2^Factorial(n): n in [0..8]]; // Vincenzo Librandi, Dec 16 2012

(Maxima) makelist(2^(n!), n, 0, 5); /* Martin Ettl, Dec 27 2012 */

(PARI) a(n)=2^n! \\ Charles R Greathouse IV, Aug 16 2017

CROSSREFS

Cf. A000079, A000142, A100731.

Sequence in context: A295580 A177956 A178981 * A326960 A067700 A270554

Adjacent sequences:  A050920 A050921 A050922 * A050924 A050925 A050926

KEYWORD

easy,nonn

AUTHOR

Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 30 1999

STATUS

approved

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Last modified December 5 13:26 EST 2019. Contains 329751 sequences. (Running on oeis4.)