A022511 Describe previous term from the right (method A - initial term is 7).

7, 17, 1711, 211711, 21172112, 122112172112, 122112171112212211, 2122112231171112212211, 21221122311721132221221112, 12312211321321121721132221221112

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• base
• easy
• nice

Comments

Method A = 'frequency' followed by 'digit'-indication.

Examples

			The term after 1711 is obtained by saying "two 1's, one 7, one 1", which gives 211711.
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 0..21

Crossrefs

Cf. A022506, A006711, A022482, A022507-A022513.

Programs

Mathematica

NestList[FromDigits@ Flatten@ Map[Reverse@ Flatten@ Tally[#] &, Split@ Reverse@ IntegerDigits[#]] &, 7, 9] (* Michael De Vlieger, Dec 16 2021 *)

Extensions

More terms from Erich Friedman