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A277191 Number of integers k in range [n^2, ((n+1)^2)-1] for which the least number of squares that add up to k (A002828) is odd. 4
0, 2, 2, 4, 5, 5, 7, 7, 9, 10, 10, 13, 12, 15, 16, 15, 18, 19, 20, 20, 24, 21, 25, 26, 26, 27, 30, 30, 31, 33, 33, 33, 37, 37, 38, 40, 42, 41, 43, 44, 46, 46, 48, 47, 51, 50, 51, 55, 53, 56, 57, 58, 61, 61, 64, 61, 63, 66, 69, 65, 68, 71, 73, 70, 74, 75, 76, 77, 79, 79, 81, 85, 80, 86, 85, 85, 89, 90, 91, 91, 92, 95, 95, 98, 95, 100 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 0..512

FORMULA

a(n) = Sum_{i=n^2 .. ((n+1)^2)-1} A000035(A002828(i)).

For all n >= 0, a(n) + A277192(n) = 2n+1.

For all n >= 1, a(n) = 1 + A277193(n).

PROG

(Scheme)

(define (A277191 n) (add (lambda (i) (A000035 (A002828 i))) (A000290 n) (+ -1 (A000290 (+ 1 n)))))

;; Implements sum_{i=lowlim..uplim} intfun(i)

(define (add intfun lowlim uplim) (let sumloop ((i lowlim) (res 0)) (cond ((> i uplim) res) (else (sumloop (1+ i) (+ res (intfun i)))))))

CROSSREFS

Cf. A000035, A000290, A002828, A277192.

After the initial zero, one more than A277193.

Sequence in context: A334149 A118003 A159296 * A335129 A035632 A114701

Adjacent sequences:  A277188 A277189 A277190 * A277192 A277193 A277194

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 04 2016

STATUS

approved

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Last modified September 21 21:32 EDT 2021. Contains 347605 sequences. (Running on oeis4.)