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A048531 a(n) is the smallest value of m such that A002378(m), the m-th oblong number, contains exactly n 1's.

%I A048531 #32 Feb 16 2025 08:32:40
%S A048531 3,10,105,1010,10203,33928,105551,335128,1054130,12313046,100573943,
%T A048531 333192303,1054092885,4261585525,30184681729,133083117303,
%U A048531 331829837885,4136557897710,11666683809854,105410706823885,333183899837885,3333333637837885,6466156610468989,33928029520312720,138242940872632303
%N A048531 a(n) is the smallest value of m such that A002378(m), the m-th oblong number, contains exactly n 1's.
%H A048531 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PronicNumber.html">Pronic Number</a>
%e A048531 From _Jesse Sealand_, Oct 06 2019: (Start)
%e A048531 a(1) = 3 since A002378(3) = 12;
%e A048531 a(2) = 10 since A002378(10) = 110;
%e A048531 a(3) = 105 since A002378(105) = 11130;
%e A048531 a(4) = 1010 since A002378(1010) = 1021110, etc.
%e A048531 (End).
%Y A048531 Cf. A048532, A002378.
%Y A048531 Cf. A048529, A048533, A048535, A048537, A048539, A048541, A048543, A048545, A048547.
%K A048531 nonn,base
%O A048531 1,1
%A A048531 _Patrick De Geest_, May 15 1999
%E A048531 a(13)-a(16) from _Lars Blomberg_, Jun 10 2011
%E A048531 Name edited by _Jesse Sealand_, Oct 06 2019
%E A048531 a(17) from _Giovanni Resta_, Oct 09 2019
%E A048531 a(18)-a(25) from _Max Alekseyev_, Jul 24 2024