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 A239971 Least k>1 such that triangular(n) + triangular(n+k) is a square. 0
 8, 4, 10, 16, 22, 6, 34, 40, 14, 52, 58, 8, 16, 76, 82, 24, 94, 100, 106, 10, 23, 124, 20, 136, 142, 25, 36, 160, 22, 12, 178, 184, 55, 46, 202, 208, 54, 220, 226, 34, 56, 14, 26, 31, 262, 36, 274, 66, 49, 89, 28, 304, 65, 316, 76, 16, 48, 84, 346, 352, 358, 86, 50, 376 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS For n>0, a(n) <= 6*n-2 because triangular(n) + triangular(7*n-2) = (5*n-1)^2. LINKS PROG (PARI) triangular(n) = n*(n+1)/2; s=[]; for(n=0, 100, k=2; while(!issquare(triangular(n)+triangular(n+k)), k++); s=concat(s, k)); s \\ Colin Barker, Mar 31 2014 CROSSREFS Cf. A000217, A232177. Sequence in context: A254767 A194184 A194217 * A082073 A244209 A156279 Adjacent sequences: A239968 A239969 A239970 * A239972 A239973 A239974 KEYWORD nonn AUTHOR Alex Ratushnyak, Mar 30 2014 STATUS approved

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Last modified March 20 11:42 EDT 2023. Contains 361375 sequences. (Running on oeis4.)