A254378 - OEIS

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A254378

Run lengths of A228495 (Characteristic function of the odd odious numbers).

1, 1, 5, 1, 3, 1, 1, 1, 5, 1, 1, 1, 3, 1, 5, 1, 3, 1, 1, 1, 3, 1, 5, 1, 1, 1, 5, 1, 3, 1, 1, 1, 5, 1, 1, 1, 3, 1, 5, 1, 1, 1, 5, 1, 3, 1, 1, 1, 3, 1, 5, 1, 3, 1, 1, 1, 5, 1, 1, 1, 3, 1, 5, 1, 3, 1, 1, 1, 3, 1, 5, 1, 1, 1, 5, 1, 3, 1, 1, 1, 3, 1, 5, 1, 3, 1, 1, 1, 5, 1, 1, 1, 3, 1, 5, 1, 1

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

OFFSET

1,3

COMMENTS

Also run lengths of A254377 = 1-A228495(n).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

EXAMPLE

A228495 begins 0,1,0,0,0,0,0,1,0, hence this sequence begins 1,1,5,1.

MATHEMATICA

Length /@ Split[Table[If[OddQ[n] && OddQ[DigitCount[n, 2, 1]], 1, 0], {n, 0, 200}]] (* Amiram Eldar, Aug 07 2023 *)

PROG

(PARI)

up_to = 65537;

A254378lista(up_to) = { my(v=vector(up_to), r=1, n=0, i=1, pb=0, b); while(n<up_to, b = (hammingweight(i)%2)*(i%2); if(b==pb, r++, n++; v[n] = r; r = 1; pb = b); i++); (v); }; \\ Antti Karttunen, Oct 01 2018

v254378 = A254378lista(up_to);

A254378(n) = v254378[n]; \\ Antti Karttunen, Oct 01 2018

(Python)

from itertools import count, islice, groupby

def A254378_gen(): # generator of terms

return (len(list(g)) for k, g in groupby(n.bit_count()&1&n for n in count(0)))

A254378_list = list(islice(A254378_gen(), 20)) # Chai Wah Wu, Mar 09 2023

CROSSREFS

Cf. A228495, A254377, A254655.

Sequence in context: A091384 A011305 A348317 * A134568 A198798 A229181

Adjacent sequences: A254375 A254376 A254377 * A254379 A254380 A254381

KEYWORD

nonn,base

AUTHOR

Jeremy Gardiner, Jan 29 2015

STATUS

approved