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A247476 A Skolem-type sequence: each pair of two terms that start with a digit k are separated by k other terms. Lexicographically earliest permutation of positive integers with this property. 4
1, 2, 10, 3, 20, 4, 5, 30, 6, 7, 40, 8, 50, 9, 11, 60, 12, 70, 21, 41, 80, 22, 23, 90, 42, 24, 13, 25, 14, 15, 26, 16, 17, 27, 18, 19, 28, 100, 29, 31, 43, 200, 51, 32, 61, 44, 33, 45, 52, 53, 34, 62, 46, 35, 47, 54, 55, 36, 63, 48, 37, 49, 56, 57, 38, 64, 400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

E. Angelini, A Skolem-like seq with no terms repeated, SeqFan list, Nov 22 2014

Rémy Sigrist, Illustration of first terms

Rémy Sigrist, PARI program for A247476

EXAMPLE

The sequence starts 1,2,10,...: there is 1 term enclosed by 1 and 10: the term 2.

Then it goes on 1,2,10,3,20,...: there are 2 terms (10 and 3) enclosed between 2 and 20.

Then, in 1,2,10,3,20,4,5,30,... there are 3 terms (20, 4 and 5) enclosed by 3 and 30, etc.

PROG

(PARI) See Links section.

CROSSREFS

Sequence in context: A252758 A249917 A176577 * A245062 A120862 A153273

Adjacent sequences:  A247473 A247474 A247475 * A247477 A247478 A247479

KEYWORD

nonn,base,nice

AUTHOR

Eric Angelini and M. F. Hasler, Nov 30 2014

EXTENSIONS

Data corrected by Rémy Sigrist, Jul 10 2019

STATUS

approved

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Last modified December 15 20:00 EST 2019. Contains 330000 sequences. (Running on oeis4.)