A038597 - OEIS

A038597

Numbers whose square is a difference between 2 positive cubes in at least one way.

13, 28, 49, 104, 147, 181, 189, 224, 351, 361, 388, 392, 507, 549, 588, 676, 756, 832, 1029, 1176, 1323, 1369, 1425, 1448, 1512, 1625, 1792, 1862, 1911, 1922, 2299, 2355, 2521, 2808, 2883, 2888, 3104, 3136, 3185, 3216, 3500, 3721, 3969, 4056, 4103, 4332

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OFFSET

1,1

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = sqrt(A038596(n)). - M. F. Hasler, Oct 05 2013

PROG

(PARI) is(n)=my(N=n^2); for(k=sqrtnint(N, 3)+1, (sqrtint(12*N-3)+3)\6, if(ispower(N-k^3, 3), return(1))); 0 \\ Charles R Greathouse IV, Oct 28 2013

(PARI) mm=820188; cb=vector(mm); for(i=1, mm, cb[i]=i^3); mb=1420608; v=vector(mb); mx=mb^2; for(i=1, mm-1, for(j=i+1, mm, d=cb[j]-cb[i]; if(d<=mx, if(issquare(d, &r), v[r]=1), next(2)))); c=0; for(n=1, mb, if(v[n]==1, c++; write("b038597.txt", c " " n))) \\ Donovan Johnson, Oct 31 2013

CROSSREFS

Cf. A038593-A038598.

Sequence in context: A063309 A098847 A161453 * A026054 A281476 A001291

Adjacent sequences: A038594 A038595 A038596 * A038598 A038599 A038600

KEYWORD

nonn

AUTHOR

Jeff Burch

EXTENSIONS

More terms from Jud McCranie

STATUS

approved