cp's OEIS Frontend

A052346 Smallest number which is the sum of two positive triangular numbers in exactly n different ways.

%I A052346 #18 Oct 21 2023 01:47:02
%S A052346 1,2,16,81,471,1056,1381,11781,6906,17956,34531,123256,40056,4462656,
%T A052346 305256,448906,200281,1957231,520731,10563906,1001406,11222656,
%U A052346 539550781,3454506,1482081,75865156,7172606106,8852431,25035156,334020781,13018281,38531031,7410406,7014160156
%N A052346 Smallest number which is the sum of two positive triangular numbers in exactly n different ways.
%C A052346 From _Chai Wah Wu_, Oct 20 2023: (Start)
%C A052346 Other terms:
%C A052346 a(35) =  42980356
%C A052346 a(36) =  19267056
%C A052346 a(38) =  1289707656
%C A052346 a(39) =  2782318906
%C A052346 a(40) =  37052031
%C A052346 a(41) =  256720506
%C A052346 a(42) =  325457031
%C A052346 a(45) =  221310781
%C A052346 a(47) =  550240551
%C A052346 a(48) =  60765331
%C A052346 a(50) =  2200089531
%C A052346 a(54) =  327539956
%C A052346 a(56) =  926300781
%C A052346 a(59) =  7629645156
%C A052346 a(60) =  481676406
%C A052346 a(63) =  4598740656
%C A052346 a(64) =  303826656
%C A052346 a(68) =  6418012656
%C A052346 a(71) =  4579579956
%C A052346 a(72) =  789949306
%C A052346 a(80) =  1519133281
%C A052346 a(81) =  9498658731
%C A052346 a(84) =  12041910156
%C A052346 a(90) =  8188498906
%C A052346 a(96) =  3220562556
%C A052346 a(108) =  13429138206
%C A052346 (End)
%e A052346 a(4) = 471 because 471 is the sum of two positive triangular numbers in exactly 4 different ways (as 300+171, 351+120, 435+36, and 465 + 6), and there is no smaller number that has this property.
%Y A052346 Cf. A000217, A052343, A052344, A052345, A052347, A052348, A053587, A064816.
%K A052346 nonn
%O A052346 0,2
%A A052346 _Christian G. Bower_, Jan 23 2000
%E A052346 a(27), a(28) = 8852431, 25035156; a(26) not yet found
%E A052346 a(26) from _Donovan Johnson_, Nov 17 2008
%E A052346 Name edited (added the qualifier "positive"), example edited, and a(29)-a(32) added by _Jon E. Schoenfield_, Jul 16 2017
%E A052346 a(33) from _Chai Wah Wu_, Oct 20 2023