%I #27 Sep 08 2022 08:44:59
%S 7,16,25,34,43,52,61,70,106,115,124,133,142,151,160,205,214,223,232,
%T 241,250,304,313,322,331,340,403,412,421,430,502,511,520,601,610,700,
%U 1006,1015,1024,1033,1042,1051,1060,1105,1114,1123,1132,1141,1150,1204
%N Numbers whose sum of digits is 7.
%C A007953(a(n)) = 7; number of repdigits = #{7,1111111} = A242627(7) = 2. - _Reinhard Zumkeller_, Jul 17 2014
%H Vincenzo Librandi, <a href="/A052221/b052221.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[1500],Total[IntegerDigits[#]]==7&] (* _Harvey P. Dale_, Apr 11 2012 *)
%o (Magma) [n: n in [1..1500] | &+Intseq(n) eq 7 ]; // _Vincenzo Librandi_, Mar 08 2013
%o (Haskell)
%o a052221 n = a052221_list !! (n-1)
%o a052221_list = filter ((== 7) . a007953) [0..]
%o -- _Reinhard Zumkeller_, Jul 17 2014
%o (Python)
%o def ok(n): return sum(map(int, str(n))) == 7
%o print(list(filter(ok, range(1205)))) # _Michael S. Branicky_, Jul 16 2021
%o (Python) # faster version generating initial segment
%o from sympy.utilities.iterables import multiset_permutations
%o def auptodigs(maxdigits):
%o alst = []
%o for d in range(1, maxdigits+1):
%o digset = "0"*(d-1) + "1111111222334567"
%o for p in multiset_permutations(digset, d):
%o if p[0] != '0' and sum(map(int, p)) == 7:
%o alst.append(int("".join(p)))
%o return alst
%o print(auptodigs(4)) # _Michael S. Branicky_, Jul 16 2021
%Y Supersequence of A119461.
%Y Cf. A007953, A242614, A242627.
%Y Cf. A011557 (1), A052216 (2), A052217 (3), A052218 (4), A052219 (5), A052220 (6), A052222 (8), A052223 (9), A052224 (10), A166311 (11), A235151 (12), A143164 (13), A235225(14), A235226 (15), A235227 (16), A166370 (17), A235228 (18), A166459 (19), A235229 (20).
%K nonn,base,easy
%O 1,1
%A _Henry Bottomley_, Feb 01 2000
%E Offset changed from _Bruno Berselli_, Mar 07 2013