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A115160 Numbers that are not the sum of two triangular numbers and a fourth power. 5
33, 63, 75, 125, 365, 489, 492, 684, 693, 723, 954, 1043, 1185, 1505, 1623, 1629, 1736, 1775, 1899, 1904, 1925, 2015, 2051, 2679, 2883, 3534, 3774, 3936, 4332, 4461, 4739, 4923, 5445, 5721, 5847, 6285, 6348, 6474, 6783, 7034, 7478, 8604, 9576, 9686, 9863 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

There are 88 such numbers up to 2*10^9, the last one in this range being 1945428.

LINKS

David W. Wilson, Table of n, a(n) for n = 1..88

PROG

(PARI) sumset_lim(a, b, lim)=my(v=[], u, t); if(a==b, for(i=1, #a, u=List(); for(j=i, #b, t=a[i]+b[j]; if(t>lim, break); listput(u, t)); v=vecsort(concat(v, Vec(u)), , 8)), for(i=1, #a, u=List(); for(j=1, #b, t=a[i]+b[j]; if(t>lim, break); listput(u, t)); v=vecsort(concat(v, Vec(u)), , 8))); v

makev(lim)=my(n=floor(sqrt(2*lim)-1/2), v); sumset_lim(v=vector(n, k, k*(k-1)/2), v, lim)

is(n)=for(i=1, #v, if(ispower(n-v[i], 4), return(0)); if(v[i]>n, return(1)))

v=makev(1e5);

for(n=1, 1e5, if(is(n), print1(n", "))) \\ Charles R Greathouse IV, Aug 17 2011

CROSSREFS

Cf. A022552, A014158, A115159, A115161, A115162, A115163.

Sequence in context: A140156 A154600 A100593 * A053179 A183347 A116350

Adjacent sequences:  A115157 A115158 A115159 * A115161 A115162 A115163

KEYWORD

nonn

AUTHOR

Giovanni Resta, Jan 15 2006

STATUS

approved

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Last modified March 30 05:12 EDT 2017. Contains 284297 sequences.