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a(1) = 1; a(n) = a(n-1) + product of the digits of n-1.
1

%I #7 Jan 23 2021 16:47:09

%S 1,2,4,7,11,16,22,29,37,46,46,47,49,52,56,61,67,74,82,91,91,93,97,103,

%T 111,121,133,147,163,181,181,184,190,199,211,226,244,265,289,316,316,

%U 320,328,340,356,376,400,428,460,496,496,501,511,526,546,571,601,636,676,721,721,727,739,757,781,811,847,889,937,991,991

%N a(1) = 1; a(n) = a(n-1) + product of the digits of n-1.

%H Harvey P. Dale, <a href="/A070280/b070280.txt">Table of n, a(n) for n = 1..1000</a>

%e a(12) = a(11) + product of digits of 11 = 46 + 1 = 47.

%t a[n_] := a[n] = (a[n - 1] + Times @@ IntegerDigits[n - 1]); a[1] = 1; Table[ a[n], {n, 1, 60}]

%t nxt[{n_,a_}]:={n+1,a +Times@@IntegerDigits[n]}; NestList[nxt,{1,1},70][[All,2]] (* _Harvey P. Dale_, Jan 23 2021 *)

%K base,nonn

%O 1,2

%A _Joseph L. Pe_, May 09 2002

%E Edited by _Robert G. Wilson v_, May 14 2002

%E Corrected and extended by _Harvey P. Dale_, Jan 23 2021