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A333548 Numbers k such that A005132(k-1) = k. 5
3, 11, 39, 248, 844, 2752, 57071, 58056875 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subtracting 1 from k gives the index of a term A005132(k-1) = k in Recaman's sequence A005132 such that subtracting k would reach 0. This is not permitted, so we must add k instead, obtaining A005132(k) = 2*k.

If A005132(k-1) = k, A005132(k) = 2*k. The converse is not always true. For example, A005132(75) = 228 and A005132(76) = 228 - 76 = 152. - Seiichi Manyama, May 02 2020

LINKS

Table of n, a(n) for n=1..8.

Index entries for sequences related to Recamán's sequence

EXAMPLE

A005132(10)=11, so 11 is a term (and A005132(11)=22).

PROG

(Python)

A333548_list, A005132_set, y = [], {0}, 0

for n in range(1, 10**10):

    y -= n

    if y <= 0 or y in A005132_set:

        y += 2*n

    A005132_set.add(y)

    if y == n+1:

        A333548_list.append(y) # Chai Wah Wu, May 02 2020

CROSSREFS

Cf. A005132, A064568, A064569, A187921, A187922, A331659.

Sequence in context: A149061 A149062 A066979 * A136775 A108153 A010911

Adjacent sequences:  A333545 A333546 A333547 * A333549 A333550 A333551

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, May 01 2020

EXTENSIONS

a(8) from Chai Wah Wu, May 02 2020

STATUS

approved

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Last modified September 19 05:33 EDT 2020. Contains 337176 sequences. (Running on oeis4.)