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%I #26 Oct 23 2023 17:58:35
%S 2,5,8,12,15,20,23,28,32,37,40,47,50,55,60,66,69,76,79,86,91,96,99,
%T 108,112,117,122,129,132,141,144,151,156,161,166,176,179,184,189,198,
%U 201,210,213,220,227,232,235,246,250,257,262,269,272,281,286,295,300
%N a(n) = Sum_{k=1..n} floor((n+k)/k) = n + Sum_{k=1..n} sigma_0(k), where sigma_0(k) is A000005(k). Also a(n) = n + A006218(n).
%C Generalized sequence b(n) = Sum_{k=1..n} floor((n+k*t)/k) = t*n + Sum_{k=1..n} sigma_0(k), where sigma_0(k) is A000005(k). Also b(n) = t*n + A006218(n).
%C Partial sums of A334954. - _Omar E. Pol_, Sep 26 2020
%F a(n) = 2*n + Sum_{k=1..floor(n/2)} floor((n-k)/k). - _Wesley Ivan Hurt_, Dec 25 2020
%F a(n) = A005843(n) + A002541(n), after _Wesley Ivan Hurt_. - _Omar E. Pol_, Dec 25 2020
%o (PARI) a(n) = n + sum(k=1, n, numdiv(k)); \\ _Michel Marcus_, Oct 02 2020
%o (Python)
%o from math import isqrt
%o def A156745(n): return n-(s:=isqrt(n))**2+(sum(n//k for k in range(1,s+1))<<1) # _Chai Wah Wu_, Oct 23 2023
%Y Cf. A000005, A006218, A153818, A118014, A002541, A334954.
%K easy,nonn
%O 1,1
%A _Ctibor O. Zizka_, Feb 14 2009
%E More terms from _Eric M. Schmidt_, Feb 28 2014
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