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Search: id:A069692
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| A069692 |
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Smallest triangular number with value of the internal digits = n; or 0 if no such number exists. |
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+0
1
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| 105, 210, 120, 136, 741, 153, 465, 171, 780, 190, 6105, 0, 1128, 30135, 2145, 5151, 3160, 1176, 4186, 0, 80200, 2211, 1225, 0, 3240, 5253, 7260, 1275, 0, 10296, 20301, 9316, 1326, 700336, 2346, 5356, 0, 1378, 7381, 0, 3403
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Subset of A000217. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 07 2006
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EXAMPLE
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a(13) = 30135 as the internal digits are 013 with value 13.
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MAPLE
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midl := proc(n) local nshf, resul, dig ; resul := 0 ; dig := 0 ; nshf := iquo(n, 10) ; while nshf >= 10 do resul := 10^dig* irem(nshf, 10)+resul ; nshf := iquo(nshf, 10) ; dig := dig+1 ; od ; RETURN(resul) ; end: for n from 1 to 40 do for t from 1 to 1000000 do tri := t*(t+1)/2 ; if midl(tri) = n then printf("%a, ", tri) ; break ; elif t = 1000000 then printf("0, ") ; fi ; od: od : - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 07 2006
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CROSSREFS
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Cf. A069691.
Sequence in context: A026066 A044337 A044718 this_sequence A088595 A146257 A075764
Adjacent sequences: A069689 A069690 A069691 this_sequence A069693 A069694 A069695
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KEYWORD
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more,nonn,base
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 06 2002
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EXTENSIONS
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Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 07 2006
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