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A205006 a(n) = s(k)-s(j), where (s(k),s(j)) is the least pair of distinct triangular numbers for which n divides their difference. 5
2, 2, 3, 4, 5, 12, 7, 8, 9, 20, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 56, 29, 30, 31, 32, 33, 34, 35, 72, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 132, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 156, 79, 80, 81 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
For a guide to related sequences, see A204892.
LINKS
MATHEMATICA
(See the program at A205002.)
PROG
(PARI) A205006(n) = for(k=2, oo, my(sk=binomial(k+1, 2)); for(j=1, k-1, if(!((sk-binomial(j+1, 2))%n), return(sk-binomial(j+1, 2))))); \\ Antti Karttunen, Sep 27 2018
CROSSREFS
Cf. A318894 (gives the positions where a(n) is not n).
Sequence in context: A014535 A210642 A263140 * A123560 A060407 A083702
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 21 2012
EXTENSIONS
More terms from Antti Karttunen, Sep 27 2018
STATUS
approved

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Last modified May 20 19:00 EDT 2024. Contains 372720 sequences. (Running on oeis4.)