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URL: https://oeis.org/A330385

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A330385

Add the odd terms and subtract the even ones, the result must always be a square. This is the lexicographically earliest sequence of distinct positive integers with this property.

3

1, 3, 4, 9, 7, 12, 5, 8, 15, 16, 25, 11, 13, 24, 39, 17, 19, 21, 23, 44, 36, 28, 20, 33, 40, 27, 32, 45, 48, 35, 85, 72, 51, 64, 133, 87, 60, 29, 31, 105, 123, 84, 41, 43, 141, 96, 47, 49, 159, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 164, 156

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

OFFSET

1,2

COMMENTS

This sequence is a variant of A329544.

All terms belong to A042965.

LINKS

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

Rémy Sigrist, Scatterplot of the first 5000000 terms

EXAMPLE

The first terms, alongside the corresponding running totals, are:

n a(n) t(n)

-- ---- --------

1 1 1 = 1^2

2 3 4 = 2^2

3 4 0 = 0^2

4 9 9 = 3^2

5 7 16 = 4^2

6 12 4 = 2^2

7 5 9 = 3^2

8 8 1 = 1^2

9 15 16 = 4^2

10 16 0 = 0^2

11 25 25 = 5^2

PROG

(PARI) s=t=0; for (n=1, 65, for (v=1, oo, if (!bittest(s, v) && issquare(u=t-v*(-1)^v), print1 (v", "); s+=2^v; t=u; break)))

CROSSREFS

Cf. A000290, A042965, A329544, A330386 (running totals).

Sequence in context: A062319 A285265 A393377 * A178590 A022463 A378116

Adjacent sequences: A330382 A330383 A330384 * A330386 A330387 A330388

KEYWORD

nonn,look

AUTHOR

Rémy Sigrist, Dec 12 2019

STATUS

approved