A081535 Sum of row n of triangle in A081536.

1, 0, 6, 14, 15, 24, 28, 40, 45, 56, 66, 84, 91, 105, 120, 140, 153, 176, 190, 210, 231, 255, 276, 304, 325, 357, 378, 408, 435, 468, 496, 528, 561, 595, 630, 667, 703, 741, 780, 825, 861, 910, 946, 990, 1035, 1085, 1128, 1178, 1225, 1275, 1326, 1380, 1431

Offset

1,3

Links

Table of n, a(n) for n=1..53.

Formula

For n > 4, a(n) is the least number k >= n(n+1)/2 such that k - gpp(k) >= n(n-1)/2, where gpp(k) is the largest prime power dividing k. - Charlie Neder, Feb 03 2019

Prog

(PARI) a(n) = if(n<5, return([1, 0, 6, 14][n])); for(k=n*(n+1)/2, oo, if(k-if(1==k, k, my(f=factor(k)); vecmax(vector(#f[, 1], i, f[i, 1]^f[i, 2]))) >= n*(n-1)/2, return(k))); \\ Jinyuan Wang, May 03 2020

Crossrefs

Cf. A034699, A081536, A081537, A081538.

Sequence in context: A190272 A107982 A341448 * A355941 A359912 A325698

Adjacent sequences: A081532 A081533 A081534 * A081536 A081537 A081538

Keyword

nonn

Author

Amarnath Murthy, Mar 28 2003

Extensions

Corrected and extended by David Wasserman, Jun 08 2004

Offset changed to 1 by Jinyuan Wang, May 02 2020

Status

approved