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A063735 Square deficient numbers. 2
1, 4, 9, 16, 25, 49, 64, 81, 121, 169, 225, 256, 289, 361, 441, 484, 529, 625, 676, 729, 841, 961, 1024, 1089, 1156, 1225, 1369, 1444, 1521, 1681, 1849, 2025, 2116, 2209, 2401, 2601, 2809, 3025, 3249, 3364, 3481, 3721, 3844, 3969, 4096, 4225, 4489, 4761 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harry J. Smith, Table of n, a(n) for n=1..1000

MATHEMATICA

Select[#^2 & /@ Range[70], DivisorSigma[1, #] < 2 # &]

PROG

(PARI) j=[]; for(n=1, 8000, if(sigma(n)<(2*n), a=n; if(issquare(a), j=concat(j, a)))); j

(PARI) { n=0; for (m=1, 10^9, if (issquare(m) && sigma(m)<(2*m), write("b063735.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 29 2009

(PARI) { n=0; for (m=1, 10^9, s=m^2; if (sigma(s)<(2*s), write("b063735.txt", n++, " ", s); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 29 2009]

CROSSREFS

Intersection of A000290 and A005100.

Sequence in context: A279456 A069560 A075494 * A056798 A036454 A115648

Adjacent sequences:  A063732 A063733 A063734 * A063736 A063737 A063738

KEYWORD

nonn

AUTHOR

Jason Earls, Aug 13 2001

STATUS

approved

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Last modified November 17 08:17 EST 2018. Contains 317275 sequences. (Running on oeis4.)