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%I #21 Feb 13 2023 12:28:44
%S 12132003,23121300,30023121,31213200,1214230043,1312432004,2342131400,
%T 2412134003,3004312142,3400324121,4002342131,4131243200,
%U 1213267345006475,1213275364005746,1214267540036573,1214273645300765,1214275640035763,1215247365430076
%N Base 10 strong Skolem-Langford numbers.
%C Self-describing numbers: between two digits "d" there are d digits.
%C a(n) has either 0 or 2 instances of any digit, hence even number of digits.
%C "Strong" means that every digit from 0 to the largest digit of a(n) must be present in a(n). See A108116 for the "weak" variant without this additional constraint.
%C Number of digits of a(n) == 0 or 2 (mod 8)
%C Largest element is a(2820) = 867315136875420024.
%H D. Wilson, <a href="/A132291/b132291.txt">Complete table of n, a(n) for n = 1..2820</a>
%o (Python)
%o def A132291gen(): # SL() is in A108116
%o for numd in range(1, 11):
%o dset = ("0123456789")[:numd]
%o s = [0 for _ in range(2*numd)]
%o for an in sorted(SL(dset, s)):
%o yield an
%o for n, an in enumerate(A132291gen(), start=1):
%o print(n, an) # _Michael S. Branicky_, Dec 14 2020
%Y Base 10 Skolem-Langford numbers are in A108116.
%Y Base 10 weaker Skolem-Langford numbers are in A357826.
%K base,easy,fini,full,nonn
%O 1,1
%A _Eric Angelini_, Jun 26 2005, Aug 10 2007
%E Edited by _N. J. A. Sloane_, Nov 18 2007