A030622 - OEIS

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A030622

Powers of 2 grouped in pairs of two digits (version 1).

24, 81, 63, 26, 41, 28, 25, 65, 12, 10, 24, 20, 48, 40, 96, 81, 92, 16, 38, 43, 27, 68, 65, 53, 61, 31, 7, 22, 62, 14, 45, 24, 28, 81, 4, 85, 76, 20, 97, 15, 24, 19, 43, 4, 83, 88, 60, 81, 67, 77, 21, 63, 35, 54, 43, 26, 71, 8, 86, 41, 34, 21, 77, 28, 26, 84, 35, 45, 65

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

When a 0 occurs as the most significant digit of the pair, it is simply ignored, e.g., "07" becomes just 7. The following pairs are unaffected. - Alonso del Arte, Mar 28 2020

LINKS

Table of n, a(n) for n=1..69.

EXAMPLE

The first few powers of 2 corresponding to positive exponents are 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048. The digits are 2, 4, 8, 1, 6, 3, 2, 6, 4, 1, 2, 8, 2, 5, 6, 5, 1, 2, 1,0, 2, 4, 2, 0, 4, 8. Grouping them in pairs, we obtain 24, 81, 63, 26, 41, 28, 25, 65, 12, 10, 24, 20, 48.

MATHEMATICA

FromDigits/@Partition[Flatten[IntegerDigits[2^Range[32]]], 2] (* Alonso del Arte, Mar 28 2020 *)

PROG

(Scala) (List.fill(32)(2: BigInt)).scanLeft(1: BigInt)(_ * _).filter(_ > 1).map(_.toString.toCharArray).flatten.sliding(2, 2).map(_.toArray).toList.map(new String(_)).map(Integer.parseInt(_)) // Alonso del Arte, Mar 28 2020

CROSSREFS

Cf. A030623, A030624, A000079, A000455.

Sequence in context: A211597 A318988 A182915 * A063456 A265646 A304158

Adjacent sequences: A030619 A030620 A030621 * A030623 A030624 A030625

KEYWORD

nonn,base,easy

AUTHOR

Alexei Kozlowski (bros(AT)spf.minsk.by)

EXTENSIONS

More terms from Douglas Winston (douglas.winston(AT)srupc.com), Nov 06 2003

STATUS

approved