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1,2

Table of n, a(n) for n=1..54.

Let r = floor(n^(1/4)). Then a(n) = n(n+1)/2 - (r^5/5+r^4/2+r^3/3-r/30).

Let n=16.

The sum of the non-quartic numbers <= 16 is 2+3+4+5+6+7+8+9+10+11+12+13+14+15 = 119, the 16th entry in the sequence.

(PARI) g4(n)=for(x=1, n, r=floor(x^(1/4)); sum4=r^5/5+r^4/2+r^3/3-r/30; sn=x*(x+1)/2; print1(sn-sum4", "))

Sequence in context: A132296 A275586 A075543 * A079509 A132336 A272370

Adjacent sequences: A132312 A132313 A132314 * A132316 A132317 A132318

nonn

Cino Hilliard, Nov 07 2007

approved