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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..25.

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)) (Alekseyev)

CROSSREFS

Cf. A077206.

Sequence in context: A101966 A184536 A089574 * A319790 A273623 A001589

Adjacent sequences:  A077204 A077205 A077206 * A077208 A077209 A077210

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 02 2002

EXTENSIONS

Corrected and extended by Max Alekseyev, Feb 15 2005

STATUS

approved

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Last modified October 22 00:52 EDT 2019. Contains 328315 sequences. (Running on oeis4.)