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%I #20 Mar 16 2022 20:13:38
%S 72,11772,771762,757770,77677782,779777700,7077772770,778777127772,
%T 7777770777090,57777777767730,7777577077877756,177677777977777980,
%U 17673737777477771772,677777977779775677756,1789771777777771777710,7747977777770507777772,298777877777767737777770
%N Smallest oblong (promic) number containing exactly n 7's.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PronicNumber.html">Pronic Number</a>
%t With[{pn=2*Accumulate[Range[430000000]]},Table[Select[pn,DigitCount[#,10,7] == n&,1],{n,12}]]//Flatten (* _Harvey P. Dale_, Aug 14 2017 *)
%o (Python)
%o def A048544(n):
%o k, m = 1, 2
%o while True:
%o if str(m).count('7') == n:
%o return m
%o k += 1
%o m += 2*k # _Chai Wah Wu_, Mar 23 2018
%Y Cf. A048543, A002378.
%Y Cf. A048530, A048532, A048534, A048536, A048538, A048540, A048542, A048546, A048548.
%K nonn,base
%O 1,1
%A _Patrick De Geest_, May 15 1999
%E a(13)-a(17) from _Giovanni Resta_, Oct 09 2019
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