A383429 a(1)=1, and for n>1, a(n) = a(n-1) concatenated with the length of the decimal representation of a(n-1).
1, 11, 112, 1123, 11234, 112345, 1123456, 11234567, 112345678, 1123456789, 112345678910, 11234567891012, 1123456789101214, 112345678910121416, 11234567891012141618, 1123456789101214161820, 112345678910121416182022, 11234567891012141618202224
Offset: 1
Examples
a(5) = 11234 and A055642(a(5)) = 5, so a(6) = 112345.
Links
- Jason Bard, Table of n, a(n) for n = 1..355
Programs
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Mathematica
A[n_]:=NestList[#<>ToString[StringLength[#]]&,"1",n-1]; A[355]
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PARI
lista(nn) = my(va=vector(nn)); va[1] = 1; for (n=2, nn, va[n] = fromdigits(concat(digits(va[n-1]), digits(#Str(va[n-1]))));); va; \\ Michel Marcus, Apr 30 2025