A081932 - OEIS

A081932

Sum of n-th row of A081930.

0, 33, 333, 4664, 51005, 616506, 7021007, 80308008, 900360009, 10004950010, 110005510011, 1200070620012, 13000078300013, 140000961400014, 1500001055000015, 16000012606000016, 170000013670000017, 1800000160380000018, 19000000171900000019, 200000001991000000020

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..20.

MAPLE

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

PROG

(Python)

def A081930(n, k):

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

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

def A081932(n):

return sum(A081930(n, k) for k in range(1, n+1)) # Pontus von Brömssen, Aug 24 2024

CROSSREFS

Cf. A081930, A081931.

Sequence in context: A210077 A210070 A258638 * A121994 A093743 A279638

Adjacent sequences: A081929 A081930 A081931 * A081933 A081934 A081935

KEYWORD