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A082607 a(0)=1; for n > 0, a(n) = least k not included earlier such that k*a(n-1) - 1 is a square. 3
1, 2, 5, 10, 17, 26, 37, 50, 65, 34, 13, 25, 41, 61, 85, 113, 145, 122, 101, 82, 293, 634, 1105, 53, 109, 185, 74, 149, 250, 377, 205, 146, 97, 58, 29, 73, 137, 221, 181, 650, 541, 442, 353, 274, 953, 2042, 3541, 5450, 409, 173, 370, 289, 218, 157, 106, 337, 698 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..56.

MATHEMATICA

l = {1}; Do[k = 1; While[MemberQ[l, k] || !IntegerQ[Sqrt[k*Last[l]-1]], k++ ]; AppendTo[l, k], {n, 50}]; l (* Ryan Propper, Jun 13 2006 *)

PROG

(PARI) a=[1]; print1(1", "); for(n=2, 100, k=1; f=1; while(f, if(issquare(k*a[n-1]-1), f=0; for(i=1, n-1, if(a[i]==k, f=1))); k++); a=concat(a, k-1); print1(k-1", ")) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), May 01 2007

CROSSREFS

Cf. A082608, A082609, A082610, A082611, A082612.

Sequence in context: A100292 A078325 A059591 * A303372 A159547 A002522

Adjacent sequences:  A082604 A082605 A082606 * A082608 A082609 A082610

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Apr 28 2003

EXTENSIONS

Corrected and extended by Ryan Propper, Jun 13 2006

Definition corrected by R. J. Mathar, Nov 12 2006

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 01 2007

STATUS

approved

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Last modified February 23 02:25 EST 2020. Contains 332159 sequences. (Running on oeis4.)