A268721 Convolution of A006068 (inverse of Gray code) with itself: a(n) = Sum_{k=1..n+1} A006068(k) * A006068(1+n-k).

0, 1, 6, 13, 26, 58, 72, 107, 160, 230, 286, 440, 558, 599, 696, 851, 1032, 1298, 1510, 1826, 2122, 2353, 2624, 3294, 3884, 4335, 4870, 5001, 5242, 5722, 6048, 6699, 7424, 8226, 8990, 10166, 11226, 12069, 13048, 14384, 15664, 16885, 18134, 19071, 20094, 21276, 22360, 25150, 27788, 30091, 32582, 34343, 36262

Offset: 0

Author

Antti Karttunen, Feb 13 2016

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 0..1023

Crossrefs

Antidiagonal sums of array A268724.

Cf. A006068

Programs

Scheme

(define A268721 (CONVOLVE 1 A006068 A006068)) ;; This version requires Antti Karttunen's IntSeq-library.
;; More stand-alone version:
(define (A268721 n) (add (lambda (k) (* (A006068 k) (A006068 (- (+ n 1) k)))) 1 (+ n 1)))
(define (add intfun lowlim uplim) (let sumloop ((i lowlim) (res 0)) (cond ((> i uplim) res) (else (sumloop (1+ i) (+ res (intfun i)))))))

Formula

a(n) = Sum_{k=1..n+1} A006068(k) * A006068(1+n-k).