A063729 Numbers k such that sigma(k)+1 is a square and sets a new record for such squares.

2, 7, 8, 14, 32, 54, 60, 72, 84, 120, 196, 252, 312, 378, 512, 540, 860, 990, 1020, 1350, 1488, 1560, 2190, 2232, 3084, 3144, 3288, 3444, 3456, 4620, 7740, 8520, 9720, 13080, 13500, 19230, 19590, 20088, 21120, 27090, 29064, 29232, 31500, 42336

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..150

Prog

(PARI) j=[]; for(n=1, 70000, x=sigma(n)+1; if(issquare(x), b=x; if(b>a, a=b; \ j=concat(j, n)))); j
(PARI) { n=0; a=-1; for (m=1, 10^9, if (issquare(b=sigma(m) + 1), if (b>a, a=b; write("b063729.txt", n++, " ", m); if (n==150, break))) ) } \\ Harry J. Smith, Aug 28 2009

Crossrefs

Cf. A063531.

Sequence in context: A063531 A063771 A064293 * A299151 A023178 A334227

Adjacent sequences: A063726 A063727 A063728 * A063730 A063731 A063732

Keyword

nonn

Author

Jason Earls, Aug 12 2001

Status

approved