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A253652 Triangular numbers that are the product of a triangular number and an oblong number. 3
0, 6, 36, 120, 210, 300, 630, 1176, 2016, 3240, 3570, 4950, 7140, 7260, 10296, 14196, 19110, 23436, 25200, 32640, 39060, 41616, 52326, 61776, 64980, 79800, 97020, 116886, 139656, 145530, 165600, 195000, 228150, 242556, 265356, 304590, 306936, 349866, 353220, 404550, 426426, 461280 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Supersequence of A083374, because A083374(n)= n^2 * (n^2 - 1)/2 = n*(n+1)/2*n*(n-1), product of triangular number n*(n+1)/2 and oblong number n*(n-1).

LINKS

Table of n, a(n) for n=1..42.

EXAMPLE

630 is in the sequence because it is a triangular number (630 = 35*36/2) and 630 = 105*6, with 105 = 14*15/2, triangular number, and 6 = 2*3, oblong number.

PROG

(PARI) {i=0; j=1; print1(0, ", "); while(i<=10^6, k=1; p=2; c=0; while(k<i&&c==0, if(i/k==i\k&&issquare(4*(i/k)+1)&&k>0, c=k); if(c>0, print1(i, ", ")); k+=p; p+=1); i+=j; j+=1)}

CROSSREFS

Cf. A002378, A000217, A188630, A083374, A253650, A253651, A253653.

Sequence in context: A207718 A262467 A225262 * A083374 A264366 A061707

Adjacent sequences:  A253649 A253650 A253651 * A253653 A253654 A253655

KEYWORD

nonn

AUTHOR

Antonio Roldán, Jan 07 2015

STATUS

approved

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Last modified December 15 11:43 EST 2019. Contains 329999 sequences. (Running on oeis4.)