A022510 Describe previous term from the right (method A - initial term is 6).
6, 16, 1611, 211611, 21162112, 122112162112, 122112161112212211, 2122112231161112212211, 21221122311621132221221112, 12312211321321121621132221221112
Offset: 0
Examples
E.g., the term after 1611 is obtained by saying "two 1's, one 6, one 1", which gives 211611.
Programs
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Mathematica
a[1]=6; a[n_]:= a[n]= IntegerReverse[ FromDigits[ Flatten[ Replace[ Replace[ Replace[ Split[ IntegerDigits[a[n-1]]], {x_,y_}->{x,Length[{x,y}]},{1}], {x_,y_,z_}->{x,Length[{x,y,z}]},{1}], {x_}->{x,Length[{x}]},{1}]]]]; Array[a,10] (* Ivan N. Ianakiev, Jul 23 2019 *) -
Python
from re import split A022510_list, l = [6], '6' for _ in range(10): l = ''.join(str(len(d))+d[0] for d in split('(0+|1+|2+|3+|4+|5+|6+|7+|8+|9+)',l[::-1]) if d) A022510_list.append(int(l)) # Chai Wah Wu, Jan 02 2015
Extensions
More terms from Erich Friedman
Comments