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 A069692 Smallest triangular number with value of the internal digits = n; or 0 if no such number exists. 0
 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, 2415, 0, 1431, 6441, 9453 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Subset of A000217. - R. J. Mathar, Apr 07 2006 LINKS EXAMPLE a(13) = 30135 as the internal digits are 013 with value 13. MAPLE 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, Apr 07 2006 CROSSREFS Cf. A069691. Sequence in context: A239827 A273521 A214082 * A212665 A242063 A228307 Adjacent sequences:  A069689 A069690 A069691 * A069693 A069694 A069695 KEYWORD nonn,base AUTHOR Amarnath Murthy, Apr 06 2002 EXTENSIONS Corrected and extended by R. J. Mathar, Apr 07 2006 STATUS approved

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Last modified August 7 10:19 EDT 2022. Contains 355985 sequences. (Running on oeis4.)