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A338773 a(n) is the number of distinct k such that 0 < k < n and a(k) + ... + a(n-1) is a square number. 2
0, 1, 2, 0, 1, 4, 1, 3, 3, 0, 1, 5, 1, 1, 1, 4, 4, 3, 0, 1, 5, 2, 0, 1, 6, 2, 6, 2, 4, 6, 1, 4, 2, 3, 4, 6, 2, 3, 1, 8, 3, 4, 3, 1, 5, 5, 2, 1, 4, 4, 7, 5, 3, 2, 4, 4, 4, 4, 5, 2, 4, 3, 1, 7, 3, 2, 8, 5, 2, 4, 4, 6, 7, 6, 2, 9, 4, 6, 4, 2, 6, 4, 5, 6, 2, 3, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

If a(n) = 0, then a(n+1) = 1 and a(n+2) >= 2.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Rémy Sigrist, PARI program for A338773

EXAMPLE

The first terms, alongside the corresponding k's, are:

  n   a(n)  Corresponding k's

  --  ----  -----------------

   1     0  {}

   2     1  {1}

   3     2  {1, 2}

   4     0  {}

   5     1  {4}

   6     4  {1, 2, 4, 5}

   7     1  {6}

   8     3  {1, 2, 7}

   9     3  {4, 5, 7}

  10     0  {}

PROG

(PARI) See Links section.

CROSSREFS

See A338774 for a similar sequence.

Sequence in context: A121583 A228924 A246862 * A194686 A302996 A266213

Adjacent sequences:  A338770 A338771 A338772 * A338774 A338775 A338776

KEYWORD

nonn

AUTHOR

Rémy Sigrist, Nov 08 2020

STATUS

approved

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Last modified December 4 13:03 EST 2021. Contains 349526 sequences. (Running on oeis4.)