A022500 Describe the previous term! (method B - initial term is 4).

4, 41, 4111, 4113, 411231, 4112213111, 411222113113, 41122312311231, 4112223111213112213111, 41122331132111311222113113, 411222321231211331122312311231

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• base
• easy
• nice

Comments

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

Examples

			E.g. the term after 4113 is obtained by saying "4 once, 1 twice, 3 once", which gives 411231.
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..23

Crossrefs

Cf. A007651, A022470, A022499, A022501-A022505.

Programs

Mathematica

a[1] = 4;
a[n_] := a[n] = {#[[1]], Length[#]}& /@ Split[a[n-1] // IntegerDigits] // Flatten // FromDigits;
Array[a, 11] (* Jean-François Alcover, Jul 13 2016 *)