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A063729 Numbers k such that sigma(k)+1 is a square and sets a new record for such squares. 1
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 (list; graph; refs; listen; history; text; internal format)
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 A080572

Adjacent sequences:  A063726 A063727 A063728 * A063730 A063731 A063732

KEYWORD

nonn

AUTHOR

Jason Earls, Aug 12 2001

STATUS

approved

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Last modified December 9 03:27 EST 2019. Contains 329872 sequences. (Running on oeis4.)