A081932 - OEIS

%I #14 Aug 24 2024 14:29:59

%S 0,33,333,4664,51005,616506,7021007,80308008,900360009,10004950010,

%T 110005510011,1200070620012,13000078300013,140000961400014,

%U 1500001055000015,16000012606000016,170000013670000017,1800000160380000018,19000000171900000019,200000001991000000020

%N Sum of n-th row of A081930.

%p isA002113 := proc(n) local digrev,d ; digrev := convert(n,base,10) ; for d from 1 to nops(digrev)/2 do if op(d,digrev) <> op(-d,digrev) then RETURN(false) ; fi ; od ; RETURN(true) ; end: A081930 := proc(n) local a,k ; a := [] ; k := 10^(n-1) ; while nops(a) < n do if isA002113(k) then a := [op(a),k] ; fi ; k := k+1 ; od ; RETURN(a) ; end: A081932 := proc(n) local nrow,i ; nrow := A081930(n) ; add(op(i,nrow),i=1..nops(nrow)) ; end: for n from 1 to 18 do A081932(n) ; od ; # _R. J. Mathar_, Apr 05 2007

%o (Python)

%o def A081930(n,k):

%o     s = str(10**((n-1)//2)-(n==1)+k-1)

%o     return int(s+s[-1-n%2::-1])

%o def A081932(n):

%o     return sum(A081930(n,k) for k in range(1,n+1)) # _Pontus von Brömssen_, Aug 24 2024

%Y Cf. A081930, A081931.

%K base,nonn

%O 1,2

%A _Amarnath Murthy_, Apr 01 2003

%E More terms from _R. J. Mathar_, Apr 05 2007

%E More terms from _Pontus von Brömssen_, Aug 22 2024

%E a(1) corrected by _Pontus von Brömssen_, Aug 24 2024