A260526 - OEIS

A260526

Concatenate the positions of digits 0, 1,..., 9 in the decimal representation of n, using 1 for the rightmost digit etc., skip it if a digit does not occur.

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 12, 12, 21, 21, 21, 21, 21, 21, 21, 21, 12, 12, 12, 21, 21, 21, 21, 21, 21, 21, 12, 12, 12, 12, 21, 21, 21, 21, 21, 21, 12, 12, 12, 12, 12, 21, 21, 21, 21, 21, 12, 12, 12, 12, 12, 12, 21, 21, 21, 21, 12, 12, 12, 12, 12, 12, 12, 21, 21

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OFFSET

0,11

COMMENTS

Sequence A260274 lists fixed points of this function.

Sequence A260519 is the same except for concatenating a 0 for digits which do not occur.

LINKS

Table of n, a(n) for n=0..68.

EXAMPLE

Consider n=1103, the digit '0' is at 2nd position (looking from the right), digit '1' in 3rd and 4th place, digit '3' at 1st position, digits 2 and 4-9 do not occur. Thus a(1103) = 2341.

PROG

(PARI) a(n)={my(p=vector(10)); for(i=1, #n=if(n, Vecrev(digits(n)), [0]), p[n[i]+1]=if(p[n[i]+1], concat(p[n[i]+1], i), i)); if(1<#p=concat(select(t->#t, p)), p[1]=Str(p[1]); eval(concat(p)), p)}

CROSSREFS

Cf. A260527 - A260529 and A260519 - A260522 for variants; A045918 for the classical "look and say" sequence.

Sequence in context: A372219 A064161 A260528 * A040133 A092538 A354571

Adjacent sequences: A260523 A260524 A260525 * A260527 A260528 A260529

KEYWORD

nonn,base

AUTHOR

M. F. Hasler, Jul 28 2015

STATUS

approved