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A045507 Concatenate powers of 2. 2
1, 12, 124, 1248, 124816, 12481632, 1248163264, 1248163264128, 1248163264128256, 1248163264128256512, 12481632641282565121024, 124816326412825651210242048, 1248163264128256512102420484096, 12481632641282565121024204840968192, 1248163264128256512102420484096819216384 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

A. Murthy, Smarandache Notions Journal, Vol. 11 N. 1-2-3 Spring 2000. [Felice Russo, Nov 15 1999]

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..80

FORMULA

a(n) = a(n-1)*10^(floor(1 + log_10(2^n))) + 2^n, with a(0)=1. [Paolo P. Lava, Oct 29 2008]

EXAMPLE

124 belongs to the sequence because it is the concatenation of 2^0, 2^1 and 2^2.

MAPLE

P:=proc(i) local a, n; a:=1; print(a); for n from 2 by 1 to i do a:=(a*10^trunc(evalf(floor(1+log10(2^n)), 100))+2^n); print(a); od; end: P(100); # Paolo P. Lava, Oct 29 2008

MATHEMATICA

Join[{1}, FromDigits/@Flatten/@IntegerDigits/@Flatten/@Rest[FoldList[List, {1}, 2^Range[25]]]] (* Vincenzo Librandi, Aug 10 2017 *)

PROG

MAGMA [Seqint(Reverse(&cat[Reverse(Intseq(2^k)): k in [0..n]])): n in [0..17]]; // Vincenzo Librandi, Aug 10 2017

CROSSREFS

Cf. A000079.

Sequence in context: A262573 A039680 A016134 * A288350 A209041 A155595

Adjacent sequences:  A045504 A045505 A045506 * A045508 A045509 A045510

KEYWORD

nonn,base

AUTHOR

Jeff Burch

STATUS

approved

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Last modified November 19 05:29 EST 2018. Contains 317333 sequences. (Running on oeis4.)