OFFSET
1,1
COMMENTS
A subsequence of 1, 11, 111, 1111, 2000, 10002, 10020, 10200, 11111,... which contains n such that A003132(n) = A055642(n). - R. J. Mathar, Nov 07 2011
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(2) = 102001 is in the sequence because 1^2+0^2+2^2+0^2+0^2+1^2 = 6 = length(a(2)).
MAPLE
g:= proc(n, s) option remember; # <= n-digit numbers with sum of squares of digits = s
option remember; local j;
if s = 0 then return [0]
elif n = 0 then return []
fi;
[seq(op(map(t -> 10*t + j, procname(n-1, s-j^2))), j=0 .. min(9, floor(sqrt(s))))]
end proc:
sort([seq(op(select(t -> t >= 10^(n-1) and isprime(t), g(n, n))), n=1..9)]); # Robert Israel, Jan 09 2025
MATHEMATICA
fQ[n_] := Plus @@ (IntegerDigits[n]^2) == IntegerLength[n]; Select[Prime[Range[100000000]], fQ] (* Robert G. Wilson v, Nov 07 2011 *)
CROSSREFS
KEYWORD
AUTHOR
Michel Lagneau, Nov 03 2011
STATUS
approved