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A077207
Triangular number index of A077206(n).
1
1, 5, 32, 126, 141, 447, 4001, 4472, 40001, 44721, 141421, 447214, 3162278, 4472136, 34641016, 109544512, 400000001, 447213596, 3464101616, 10954451150, 31622776602, 77459666925, 316227766017, 774596669241, 1414213562373, 4472135955001, 14142135623731
OFFSET
1,2
PROG
(PARI)
{rT(m) = ceil((sqrt(8*m+1)-1)/2)}
{T(n) = (n*(n+1))/2}
m=1; for(n=2, 50, k=rT((m%10)*10^(n-1)); while(T(k)%10==0, k++); m=T(k); print1(" ", k)) \\ Max Alekseyev, Feb 15 2005
CROSSREFS
Sequence in context: A184536 A363411 A089574 * A319790 A273623 A359522
KEYWORD
base,nonn,changed
AUTHOR
Amarnath Murthy, Nov 02 2002
EXTENSIONS
Corrected and extended by Max Alekseyev, Feb 15 2005.
a(25) and a(26) added by Robert C. Lyons, Nov 16 2024.
STATUS
approved