

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



PROG

(PARI) A205006(n) = for(k=2, oo, my(sk=binomial(k+1, 2)); for(j=1, k1, if(!((skbinomial(j+1, 2))%n), return(skbinomial(j+1, 2))))); \\ Antti Karttunen, Sep 27 2018


CROSSREFS

Cf. A318894 (gives the positions where a(n) is not n).


KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



